That doesn't match my experience in Boston. Multiple neighborhoods I lived in had walking access to Stop & Shop, Star Market, Trader Joe's, Whole Foods, Target

That doesn't match my experience in Boston. Multiple neighborhoods I lived in had walking access to Stop & Shop, Star Market, Trader Joe's, Whole Foods, Target, bfresh, cheap overstock/clearance stores, a farmers market, and other independent grocers, many catering to nationalities/ethnicities with large subcommunities in the area. Just a train or bus ride away I could go to Market Basket, Roche Brothers, Wegmans, a worker owned-co-op, and more farmers markets and independent grocers. Costco was a longer train ride away, but accessible if you wanted something specifically from there. Delivery is more economical because of the shorter distances involved. You can see this yourself by doing a map search. In rural areas I've lived, one is common, sometimes zero within a fifteen minute drive. Suburban areas might have two or three regional supermarkets, plus Walmart, Target, Costco and/or Sam's, but always way fewer within the area covered by the same travel time.