Sure, there are always extenuating circumstances and outliers, but Walmart is an objectively bad company to work for. They prioritize upper management and shareholders over the vast majority of their workforce, who can go suck an egg for the most part. They treat their employees like an expendable resource, so the employees they DO get are pretty terrible, because they have no incentive to care. "The company pays me squat, they don't give me enough hours to qualify for benefits, they treat me like garbage, and I'm likely to get canned at any moment for the dumbest reasons. Guess I'll just do the bare minimum, not stick my neck out, and stay out of sight." Not the type of employee you want to have.
Meanwhile, go to some place like Costco or Aldi and the employees there are (generally) pretty stellar in comparison to other stores.
I definitely get what you're saying, and Walmart is vastly different than any sign company out there (or any other type of company, for that matter) due to the sheer size, but the point still stands. If you treat your employees more like a Costco than a Walmart, you're going to have better employees in the long run. AND you'll get a reputation for being a good employer and people will actively seek out employment with you.
Excellent real world comparison. Let's also not forget the strategic community destroying approach to how WalMart chooses where to locate, works over the local government to receive favorable tax abatements, undercuts the pricing in order to starve the nearby small, local business community, hammers its vendors on their wholesale prices, etc.