Corner stores in NYC have some advantages, competition. If

In the burbs and rural areas, the stores are spread out, and if you have a shitty store a couple miles closer than a decent store, they can just produce the cheapest crap and sell it to you for exorbatent prices.

New Yorkers are ok with walking a few blocks. So if your corner shop can't complete another one 2 minutes away will draw away their customers.

Even corner shops in Baltimore and DC are pretty anemic comparatively, but they tend to have more actual restaurants peppered about.