It depends. I used to live in Belgium and now in Luxembourg and both countries have been removed from an international gray list of countries refusing to share banking information (they do share now).
Old article from 2009:
https://www.politico.eu/article/luxembourg-and-belgium-remov...
There was a time where people would literally come to Luxembourg with duffelbags full of bank notes and nobody would ask anything.
But these times are definitely gone.
> I’m still of the predilection that states should just give up on trying to police money flows
Having been directly hit by this and KYC/AML making my life miserable I fully agree with that.
Some people have their entire bank account frozen, sometimes for months, because they make one wire transfer of a few thousands EUR to another country: happened to someone I know (who's an AML specialist, which is ironic) for buying a watch in Dubai and happened to someone else I know for... Paying for his wedding (which was taking place in another country than the one he was living in). His wedding nearly got cancelled due to zealots at the bank convinced they found an international drugs trafficker or something...
The worst of the worst is that everybody at the bank is convinced they're some super important person, part of a global elite secret service or something, where nobody can talk. Worse than the mafia. And that they'll lose their job or go to jail if they ever mention to the client why their account is getting frozen.
It's all pathetic really.