If you accept cash in person, AML in does not apply. AML has to do with bank deposits with a single purchase.
its a little more complicated then that.
try having more then$10k in a suitcase when you go to an airport or at a border check.
but the whole bank deposit thing is mainly due to the ease of noticing and finding people doing it. not so much a difference of the law. just the survellance capabilities
in short if ur accepting and giving out large amounts of FIAT as part of a business that swaps fiat for other things. then expect to have to explain yourself
it does not matter if its for legit purposes or not. it does not matter if its a bankers cheque or a bank note or a wire transfer the law is the same.
the only difference is the level of surveillance needed to find out who moved what to where, and for what reason.
so if you dont want the headaches, dont touch fiat.