Employees are working yet still they need government assistance to offset the low wages. Walmart knows this and one might argue they incorporate in their business planning. Why pay employees to work full time, when you can pay them part time, reduce your labor costs and have the state pick up the rest of the expenses (i.e. medicare, Foodstamps)
Walmart executive's know this is a win/win for them, they get the labor they need and pay little for it. This is not something that just happened overnight. It's corporate greed on a massive scale that hurts everyone but no one cares because Wallstreet see's the profits rolling in.
Deceptive businesses like Walmart are consistently fucking us all, and nothing is done about it. The tax breaks they receive are enabling this behavior.
End rant.