When cash is outlawed, only outlaws will have cash.
Louisiana has outlawed cash for second hand goods. They claim it’s to prevent criminals from selling stolen goods. Maybe it is, but it’s also a dandy control mechanism to find out where all the money is going and who’s buying what. When you know where it’s going, it’s much easier to take it away through taxes.
I see some possible outcomes from this law.
It could do exactly what’s intended with no negative side effects. (I give that outcome long odds.)
A lot of businesses could suffer losses. Many could shut down completely.
More and more business could be done “off the books.” That would make more people criminals who weren’t before. When government passes stupid laws that are ignored, respect for all law is diminished. Maybe that’s not totally a bad thing. Too many dumb laws are taken seriously as it is.
One interesting result is that it could be an incentive to develop alternatives to cash that also are not traceable. We could all decide to do business in something like Canadian dollars. We could make up a new local currency. Precious metals could be exchanged. Heck, people could set up a bookkeeping system of credits and exchange them in a totally independent economy. Hybrids of different exchange systems could come into play.
Business could take place totally outside the governmental system. Maybe this law is a good thing in the long run, as it’s a wake up call to the way money works.