Hell it is already illegal to carry over a certain amount of cash in some areas....
The Banks are forced to snitch on you if you pull out a certain amount in cash as well....
My neighbor informed us of a problem, his wife works at the police station and hears about details of all calls. Some stores are reporting counterfeiting to the cops. Cops go to the store and check the money and the perp (customer). The money is legit ($20 or $100 bills). Seems that the stores are using new marker pens to detect counterfeits, and the pens only pass new bills as genuine, not older ones! Not good for people like us, who pay cash often and sometimes pull bills from our hidden stash to spend. So now we're rotating our old bills for newer ones.