"but it was impossible to find anyone there capable of reading their own name tag"
Depending on region, Wal-Mart associates make around $10 - $12 / hour, which is no longer a living wage for adults in the US. Most have 2nd jobs just to pay the rent, many are not high school grads, many are over 50.
The same is true for Home Depot, Target, and the other major retailers. Add to this the rip-off health benefits scheme at Wal-Mart and it's no wonder only the most desperate and least qualified are working at these places.
I used to feel disdain for these people, blaming them for being just lazy stupid slackers. Until I got a little first hand experience with the situation. Now I feel sorry for them, most are trapped in these kinds of positions with no real way out.