The solution to what? There's literally no problem that needs solving here. It's easy to accept cards and also easy to accept cash. Neither is particularly expe

The solution to what? There's literally no problem that needs solving here. It's easy to accept cards and also easy to accept cash. Neither is particularly expensive or hard to deal with. If you really want to accept just one and not the other, that's fine, too. If you occasionally get a confused customer who accidentally consumes your services and then only has cash to pay, that's not a big deal of course. And the reverse is also no big deal -- if you don't accept cards, and the customer don't have cash, you just point them at the nearest ATM (often in the same store, since this is a common way to avoid credit card merchant fees) Either way is just not that big a deal.