The concept of an economic exchange medium precedes and supersedes civilization. Even the most primitive cultures had rudimentary money systems, mostly based on precious metals. People are not going to go around killing each other for seed corn and constant barter gets to be a pain in the ass.
I don’t disagree. I would say this.... if economic apocalypse happens, or whatever type of apocalypse.... it will be a couple of years before the savages are all killed off before civilized persons start being able to trade gold for goods or services.
You are not taking into account the feral human population