Minimum wage is supposed to be a reflection of the cost of living (not necessarily enough to fully cover the cost of living, but enough to be a meaningful step towards is). This of course makes a federal minimum wage fairly useless for many parts of the country as minimum wage is not even remotely close to the cost of living, but the idea is to try to at least give working people (of course you've demonstrated plainly your disdain for working people in the past) a chance to try to exist.
So while Walmart is, in that town, paying quite a bit more than the federal minimum wage, they are not actually paying a wage that is in any way adequate for someone to live there. Put it another way, if the cheapest room you can possibly rent in town is $2,000 per month and the only job you can find in that town pays $1,500 a month would you take that job or go look elsewhere for work?
That said Walmart is known for keeping large number of people (ie, its own employees) on food stamps across the country (and beyond as well).