Once upon a time I lived near the Prague city centre, and if the intent of such a corner shop is to rip off tourists and one-time visitors, the locals don't mind - at least as long as cheaper alternatives off the most notorious areas exist and are usable for them (Lidl etc.)

Quite to the contrary, the locals are sometimes happy to have such overcharged options at hand, for example if they are throwing a party and find out that they are short on vodka+cigs, and it is 1 am and all the regular shops are closed.