You have to be careful when you start talking about "people on welfare" and "poor" people because of the stereotyping involved.
I would agree that people who often don't have ready access to transportation (as in, "Let's drive to the grocery store and buy groceries.") often buy food from convenience stores which is always garbage food because it is .. well... more convenient than taking the bus to the grocery store across town and bring back several bags of groceries on the same bus.
Way, way off topic now...