ELI5 How do rich people just hide their money in offshore bank accounts? Do they just call up the bank and say I want transfer such and money? How come the original bank doesn't catch on?
There's law firms that specialize in this sort of thing. If you remember the Panama Papers from a few years ago, those were internal documents from one of these firms. Banks don't catch on because they like making money and pretending its not happening is often more profitable than calling the cops.