Because gods forbid employees have a say about how things are run, even though they're what makes the place work.

I saw a study in Sociology class once, that said that across all industries or any job imaginable, what makes for an unhappy job is a combination of low pay and having absolutely no say in things, no power to control your work environment. Most retail/food service places are run so that you have no control over anything (it's all decided by people who have never done your job) and the pay generally blows.