If you spend 4.60 per day on unprocessed food and a little meat you can get high quality food. But you need to cook it. Or you can basically starve on chips and soda. Now if your unemployed / underemployed and have free time foor cooking it's not unreasonable to shop at whole foods. Assuming you don't need to watch kids / elderly / or the disabled.

Though transportation is often a major issue keeping people shopping at the corner store.