Here in Montreal (perhaps also in other large cities) I can order groceries online from any of the major supermarkets and have them delivered to me (mind you, I don't have a car) for a reasonable minimum order value and a mere $2-3 extra. Maybe you are intentionally not targetting these cities, otherwise the idea is not really new at all.

You want to see a grumpy clerk? Go to Switzerland and forget to put the little sticker on your bags of produce. Damn.