That's the thing: when your grocery store is a short walk away, you don't buy groceries for the whole week. You just duck into the store on the walk home or you walk over at lunch. You buy things for that evening or a few days at most. Having to plan for a whole week of meals seems normal to us, but it's an adaptation to the fact that we live too far from grocery stores. With our large fridges, cabinets, pantries, and chest freezers, we basically turn part of our homes into well-stocked convenience stores so that we can go out as little as possible.