It’s not even remotely the same thing. Anyone can become a salt farmer. Only a select few control and make dollars.
Discussion
Currency only works as currency if its a limited resource. If anyone can and does become a salt farmer. Then salt is pointless.
Iirc there are two rules to currency. It has to have few uses (you can't use wood because wood is useful) and it has to be limited. That is the reason bitcoin has a max ammout that will ever be issued.