The costs are just one side of it. A good reason to accept both cash and cards is that customers like that. No doubt it would be cheaper to stock only one brand of cereals and yet nobody does that.
If this is the argument, though, then it's a good one to let the market sort out. If customers have a strong enough preference for cash that it outweighs the costs, businesses can figure this out and accept cash.
Different stores can have different options in terms of how they handle cash. Costco only has one kind of toilet paper. Target has 10. There are pluses and minuses that they can weigh themselves.
I was thinking it's one argument for the store that has the OPTION to go cashless and might not - just so as to serve more customers.
But the store is not deciding on its own. For example if costs are pushed by outside forces too far one way or the other. Say, if the tax authority makes it hell to accept cash. Well then the store does not really have the option. The decision has been made for them.
