Wildcat banks were far from common even in the antebellum United States & history offers many examples of commercial banknotes that were literally "as good as gold"

See The Fable of the Cats by George Selgin. Excerpts: 

"No adjective, first of all, could be less suitable than "light" for describing the state of bank regulation on the eve of the "Free Banking" era. Instead, as Bray Hammond observes in his monumental, Pulitzer-prize winning study of antebellum banking, “the issue was between prohibition and state control, with no thought of free enterprise.” In the Western territories banking was simply illegal, while in many frontier states only one or two banks were tolerated. Only the Northeast saw anything approaching open competition, and even there every new bank had to be approved separately by a state legislature that was likely to have been encouraged by ample bribes.

Two requirements to which all free banks were subject deserve particular attention. First, branching was strictly forbidden: every free bank was a "unit" bank. Second, free banks had to secure their notes with specific collateral, usually consisting of various state and federal government bonds, as well as some railroad bonds. The collateral had to be surrendered to state authorities before the banks opened, so that, if any failed, it might be sold off, and the proceeds employed to pay off noteholders. That, at least, was the theory. Unfortunately, as we'll see, things didn't always work out that way in practice.

So "free" banks weren't free to do whatever they liked. But even if they had been, antebellum banking as a whole wouldn't have been "lightly" regulated, because most antebellum banks weren't "free." Only 18 of the 34 states established before the Civil War embraced Free Banking at one time or another, with Michigan doing so twice. And in some of these few, if any, free banks were ever actually established—a fact that's itself at odds with the claim that such banks were always lightly regulated. Chartered banks, in the meantime, continued to exist and to be established alongside "free" ones. In all, of some 2,450 state banks established between 1790 and the start of the passage of the National Currency Act in 1863, only 872, or a little over a third, were even nominally "free."

That most antebellum banks weren't "free" itself means that most weren't wildcats, for all authorities agree that wildcat banking only occurred where Free Banking laws were in effect. But wildcats were rare even in those places.  Outside of the (Old) West, it was entirely unknown, and in the West itself it wasn't all that common.

Economists and historians have used several criteria to distinguish wildcats from legitimate banks, including how long they lasted (usually a year or less), how many notes they issued relative to their capital (many), how much holders of their notes managed to recover when they failed (no more than 95 cents on the dollar, and often much less), how much specie they kept on hand (not much), and how many people lived where they ostensibly did business (typically, no more than a few hundred). Because different scholars have emphasized different criteria, careful estimates put the total number of wildcats as low as several dozen and no higher than 173, with no more than 90 or so ever present during any one year.[2]"

"So there weren't many wildcats. But there were certainly some; and that there were any compels us to ask why.

That the bad apples were vastly outnumbered by legitimate banks, and that they flourished in no more than five states—Michigan, Minnesota, Indiana, Wisconsin, and Illinois—and often only briefly, suggests that, far from illustrating the inevitable consequences of allowing private firms to supply currency, they were products of peculiar circumstances.

The record bears this out. Take the case of Michigan. The first state to pass what it called a "general banking" law, it also experienced the first, and by all accounts the worst, outbreak of wildcat banking. The stories about kegs of nails and glass masquerading as specie, and of strongboxes full of real specie being rushed from bank to bank one step ahead of the inspectors, all come from it, courtesy of Alpheus Felch, Michigan's governor from 1846 to 1847, and its bank commissioner from 1838 to 1839, when the wildcatting took place.

Just about everything that could possibly have gone wrong with Michigan's free banking law did, starting with its timing. The law, passed by an overwhelming majority (Felch was one of only four representatives who dissented), took effect on March 15th, 1837. Less than two months later, on May 10th, the Panic of 1837 struck, causing New York's banks to suspend payments. Soon banks were suspending all over the country. On June 22nd, Michigan passed emergency legislation allowing its banks to suspend payments until May 16th, 1838.

Although 14 banks were doing business in Michigan at the time of the suspension, they were all chartered banks: no free banks had yet been set up. And that might have been the end of that, had the June 22nd legislation not extended the privilege of suspending payments to any free banks set up before it expired! So it happened that brand new banks—banks that had yet to prove themselves capable of keeping a promise—were allowed to go into business, and to take full advantage of the government's assurance that their notes were adequately secured, without having to fear being put to any test for the better part of a year. "What a temptation was this," Felch later recalled, "for the unscrupulous speculator. We can hardly be surprised at the scenes which followed, and which marked the period as a most wonderful epoch in financial history."

Having rolled a red carpet out to shady bankers, Michigan tried to make up for it by assigning Felch and two other newly-appointed bank commissioners the Herculean task of inspecting all the banks in the state at least once every three months. It was these commissioners who found themselves chasing after boxes of gold, the mere possession of which, together with an oath sworn by a bank's directors, sufficed to meet the law's capital and specie requirements.

The commissioners were quickly overwhelmed by a "fearful amount of fraud and perjury," for before a year had passed, 40 new banks sprang into being. Though these collectively swore to a nominal capital of almost $4 million, little of that was ever actually paid in. Many did business, or pretended to, from remote places—if not where wildcats literally roamed. And almost all failed in short order. Finally, commencing April 16th, 1839, the government closed the door to new free banks. Come December, only four were left. Thanks to the shoddy collateral with which those banks were allowed to secure their notes, including over-appraised farm mortgages and personal bonds, the public, apart of course from the bankers themselves, ended up at least a million dollars poorer.[3]

So Michigan's experience was indeed disastrous. But nothing could be more mistaken than to suppose that the faults of its first free banking law (for it would try again, in 1857) were faults of U.S. style "free banking" per se, let alone of any and all private currencies. Even Alpheus Felch, who opposed Michigan's arrangement from the start, and who witnessed its utter failure, knew better. Even its badly flawed general banking law, he observed in 1878,

was not without some good features, but it came into existence at a most unfortunate time, and the keenness and unscrupulousness of desperate men, taking advantage of its weak points and corruptly violating its salutary provisions, used it to public injury.

The proof of Felch's opinion consists of the numerous instances, including Michigan's own when it tried Free Banking for a second time, in 1857, in which more carefully designed and thoroughly enforced Free Banking laws were quite successful. New York's Free Banking system, launched not long after Michigan's, was among the success stories. Though it got off to a rough start, with several free banks failing in 1842, and those caught holding their notes incurring large losses, losses fell steadily after that. During the 1850s, the overall loss rate on notes issued by New York's free banks was less than 0.1 percent. By the 1860s it had become negligible.

Wildcat banking was unheard of in New York, as it was in most states with Free Banking laws. The sole exceptions, apart from Michigan, were Wisconsin, Indiana, Minnesota, and Illinois; and whether wildcats were important in any of them is controversial. According to most economic historians, including Gerald Dwyer,

There is no evidence that free banks in these states generally were characterized by continuing fraud to transfer wealth from passive noteholders to shrewd bankers. There also is little evidence supporting a generalization that these free banks were imprudent, let alone financially reckless.

Although free banks in these and other states failed, and did so more often than chartered banks, misconduct usually had nothing to do with it. Instead, Dwyer continues,

banks' losses occurred sporadically when developments outside the banking systems decreased the demand for the banks' notes or decreased the value of the banks' securities.

The failure of several dozen Wisconsin free banks in 1861, for example, appears to have been entirely due to their investment in Southern-state bonds. Because those bonds traded at or above par before the threat of secession loomed, it's absurd to suggest that these banks issued notes "without any underlying asset."  Still, the bonds lost much of their value once hostilities began, leaving their holders with heavy losses.

Admittedly, the line separating wildcats from honest banks that ran into hard times could be very fine. Consider the case of Illinois. Its original free banking law was far from perfect, and more than a few "banks" that did little but issue notes were among the 145 firms established under it by 1861. Still, most authorities agree with Francis Phillippi, the author of an 1896 thesis on the history of banking in Illinois, that up to then

This system worked well…so far as the security for the circulation was concerned. Fourteen banks had gone out of existence, and had had their affairs wound up before 1861. All their notes redeemed without loss to the holders except in one case a loss of three percent was sustained.

Even in that unique case, noteholders ultimately received 88 cents on the dollar. This record was especially remarkable in light of the severe panic that swept through the country in 1857, putting paid to many banks elsewhere. In fact, Phillippi says, the Illinois free banks proved themselves so well that they "afterwards enjoyed increased confidence" in the stability of their currency.

Yet, paradoxically, the 1857 Panic also appears to have contributed to the system's ultimate, spectacular failure. As Dan Du explains, having first forced many Eastern banks to suspend specie payments, that event subsequently "drained specie from Illinois owing to a lack of commerce." A poor 1858 crop only made matters worse. During that year alone, Illinois banks' specie holdings declined 63 percent. By May, those outside of Chicago had also stopped paying specie on demand. Yet because they were considered more than adequately secured, their notes stayed current throughout the state, satisfying a genuine need. Had it not been for those notes, Du observes, not only ordinary payments but "everything in the way of settlement of domestic balances and local improvement must have come to a dead halt."

The demand for suspended banknotes, and the profits banks could make by satisfying it, were so great in fact that 81 new free banks were established between 1858 and 1861, 66 of them in 1860 alone. By October of that year, the banks had issued over $11 million in notes on specie reserves of less than $303,000. But those notes were amply secured by over $12 million in state government bonds held by state authorities.

Or so it seemed. The hitch was that, of those $12 million in bonds, over $9.5 million were from states that eventually joined the Confederacy. Illinois's free banks thus suffered the same fate as Wisconsin's: as the threat of secession grew, the backing for their notes shrank. On the eve of the Battle of Fort Sumter, most Southern-state bonds were worth about half their par value. Within a year, 90 banks closed their doors; and this time holders of their notes lost millions.

Were the failed Illinois banks "wildcats"? According to Rolnick and Weber, they weren't: they were simply victims of force majeure, having never intended to defraud anyone. But Du disagrees. They were wildcats, he says, because, besides having never been prepared to redeem their notes on demand in specie, many didn't even have a discernible place of business. Nor did they make any loans, their profits having instead consisted entirely of interest drawn on the bonds securing their notes. "People needed the currency they produced at a time when money was scarce," Du says. "So the community acquiesced in their conduct."

But, the debate continues, if the public "acquiesced," in what sense can the banks be said to have bamboozled it? Would having no banknotes at all to trade with really have been better than having to rely on suspended ones?

It may never be possible to answer such questions decisively. But what can be said is that, even by the most generous reckoning, wildcat banking was exceptional."

"In truth, antebellum banknote discounts were for the most part neither a consequence of the lack of regulation nor a reflection of distrust of their issuers.  Default risk was sometimes a factor, to be sure. But when it was, shopkeepers and banks tended to refuse them altogether, leaving it to professional note "brokers" to deal with them, much as they dealt with notes of banks that were known to be "broken," but which might yet have some liquidation value. Discounts on "bankable" notes, on the other hand, reflected nothing more than the cost of sorting and returning them to their sources for payment in specie, plus that of bringing the specie home. This explains why, whatever the discounts placed on them elsewhere, most notes traded at par in their home markets.

Thanks to the combination of a large country, poor (though rapidly improving) transportation infrastructure, and unit banking, when notes traveled any substantial distance from their source, getting them redeemed could be quite costly. In smaller nations, and especially those, like Scotland, where banks were allowed to branch nationwide, banknote discounts were unknown: the fact that there were many different banks of issue, with varying assets, didn't prevent such nations from having "uniform" banknote currencies. Even Canada, which was geographically as large as the United States, but much less populous and with a far less developed internal transportation system, managed (with the help of several private clearinghouses) to achieve a uniform currency, based on the notes of several dozen commercial banks, by the early 1890s.[4]"

Had it not been for unit banking, the United States might well have had a uniform state banknote currency before the Civil War, thanks to its by then impressive railroad network. Even with unit banking, it came a lot closer than most people realize. Despite already having had over a hundred banks of issue at the time, with hardly any branches, New England managed, with the help of the Suffolk System—an early, Boston-based banknote clearinghouse—to achieve a uniform currency as early as 1824.

By the early 1860s, the rest of the country had nearly caught up to New England. To prove the point, some years ago I asked what loss someone living in October 1863, would have suffered had he or she purchased every non-Confederate banknote circulating at the time for its declared value, and then sold the lot to a New York or Chicago note broker for the broker's advertised price. To allow for a maximum loss, I considered any note the brokers listed as "doubtful" to be worthless. Even so, the total loss in either market amounted to less than one percent of the investment."

"Canada's wasn't the only private currency system that was head and shoulders above any 19th-century U.S. system. The Scottish system was just as noteworthy for its stability as well as its efficiency. Yet Scottish and Canadian banks were in many respects more genuinely "free" than their U.S. counterparts. Until 1845 the Scottish banks were hardly regulated at all, except by Scots contract law. Besides being free to branch nationwide, they weren't obliged to "secure" their notes with any particular assets, or (prior to 1845) to maintain any particular specie reserves. Entry into Scottish banking was also free for companies whose shareholders accepted unlimited liability: until 1858, the privilege of limited liability was limited to three "chartered" banks only. Indeed, in British as well as the Continental usage,  "free banking" and its equivalents ("le banque libre," "bankfreiheit") refer to genuinely free banking of the Scottish sort, not the phony antebellum U.S. version."