[zalew]

competitors from the same street or at least competitors from the same industry have such terminals.

Same street or same industry doesn't mean focusing on the same clients. If most of your clients come for milk, bread & butter, it doesn't make sense to install hardware just because 2 dudes want to pay card for a pack of cigs.

I have 2 shops like that near me and both run well. The one which has more products and card payment obviously earns more and you can see that, but it doesn't mean that it's not a win-win situation, nor that the main reason of one's bigger success is the presence of a terminal.