Given all the problems of money laundering and black market money entering the market why does the US have a fungible currency at all?
If I put my totalitarian hat on it would make sense for every dollar bill printed to have a unique hash assigned to them and printed on them and for the government to offer a service for checking a list of "banned hashes". Something which anyone can use to look up/scan bills with to check validity.
This could've implemented a long time ago but the US hasn't done so yet. I'm guessing there are some good reasons they wouldn't do it (besides backlash from the black markets and libertarians). What would be some of those reasons?
A particular application that comes to mind is that Private Companies/Businesses could also put "holds" on cash when they receive it, and release those "holds" when its spent. If cash is stolen before the hold is released then the criminals that do so would not be able to spend that money at all.