Citation very much needed. It depends on what you mean by "working".
There's references to tax evasion going back before the Roman Empire. For an example from the era of the Roman Empire, the topic of tax evasion is where the story of "give to Caesar what is his" (Mark 12:17) comes from. (I've found earlier Greek references going back to at least 300BC, but that's the easiest example to verify).
The state works better when it has funds to deliver on those plans - though there are many other factors that can disrupt it such as incompetence and corruption.
"Money laundering" may be a recent term, but it is not a recent concept. In fact some notable conquests on the ancient world wouldn't have been possible without concealing ill-gotten funds. It was a common tactic for avoiding paying tribute to a neighbour who defeated you.
Here's one example to ponder about: if we had this kind of surveillance earlier, would things like the Civil Rights Movement and generally the 60's counterculture come about? I.e. the era of "sex and drugs and rock'n'roll"? If only the authorities had the tools that they have today, oh boy! Don't like the liberation of sex? Is rock'n'roll the Devi's music? Fine. We'll close your PayPal account.
Privacy is very important for having a free society and freedom of expression. Financial privacy should be no exception.
If you measure anything, infant mortality, poverty, murder rates, diseases, nutrition, education, which of them fit any sensible definition of 'well'?
In my case, "worked well" meant something like a mix of: a) the world did not end, and b) everyday life in developed societies (which previously did not have total financial surveillance, but are now eager to achieve it) was more or less the same then as it is today.
In fact, to expand on b), it seems to me (admittedly from a completely intuitive and unquantified perspective) that we are quickly losing civil liberties today and that this aspect was better in the past.
You can apply the same style of reasoning to end-to-end encryption. Various actors are aiming for total surveillance in that area too, it is most likely a terrible idea and we have precedent that the world works reasonably well without it.
> Sure, why not? It has worked for many years before.
Taxing on trust alone is exactly where this little thread started.
as i understand, the "overwhelming majority" (lower and middle class) are not the focus of the problem here as they rarely use tax havens to circumvent taxes anyway (it's probably not cost effective). this is all about those who have the funds and motives to circumvent taxation, who happen to be a minority - even thought they're not a minority when it comes to taxable income; the 1% or whatever.
as for the rest of your argument, i don't completely agree. while you're probably right in practice, i.e. the authorities would have used their tools against those movements, the goals of those movements were different. the civil rights movement was probably illegal at the time but the goal was to change the laws to make it legal. same for sex. no millionaire wants to make tax evasion legal, as that would affect all tax payers, even those of the lower and middle class. they want that only for themselves.
i agree that (hard) drugs are probably a comparable example - it's illegal and puts a strain on society. on the other hand, use of hard addicting drugs can be categorized as an illness. so should we label money hoarding and tax evasion an illness? offer treatment options? allow them supervised safe spaces to evade taxes so we can offer them help?
i'm not convinced that financial privacy whould be no exception. there must be limits if it affects the others. i also don't think environmental pollution should be an issue of privacy - you shouldn't be able to pollute the air and claim it's nobodys business, as your factory stands on your own private plot of land.
The terms like "money laundering" are only recent and swept through without properly understanding the privacy implications (and probably didn't envisage the pervasiveness of modern electronic surveillance & data breaches in today's digital world).
Anyhow, advancements in cryptographic Zero-knowledge proofs could hold the key in solving some of these problems (proof that funds are clean without reveling the source). Currently there are some scalability problems, but progress is being made so I'm hopeful. Wikipedia has a good write-up about the basics of ZKP https://en.wikipedia.org/wiki/Zero-knowledge_proof