I'd be really interested in the particulars of your version of the math, Loren.
I question your point 2) in particular or maybe I'm just not reading it correctly. Generally speaking, full time employees work more hours than part time employees. Full time employees are typically eligible for benefits while part time employees typically are not. You seem to be saying that employees with benefits work fewer hours. Or perhaps you mean they don't work as well--those benefits make them less productive. Or perhaps you are referring to the fact that part time employees often cobble together a living out of two or three and occasionally more jobs, just to make ends meet.
As far as raising people above their supervisors: That doesn't follow and so what? As it happens, I know that I am paid more than my immediate supervisor but that is due to a vagary in the pay structure and job classification/degree structure of my company. He is still my supervisor, is still entitled to my respect and entitled to have me report to him and perform tasks and projects as assigned. Now, I think the company is wrong in this particular instance to pay him less than I am paid as he is clearly worth far more than I am. However, it is a large company with a fairly rigid structure.
I hate Walmart because I consider it to be a destructive cancer for precisely the reasons others have already mentioned: They engage in predatory pricing, underpay and abuse employees who have few other options, drive out locally owned businesses who are unable to compete with Walmart's vast bulk purchasing power and whenever they decide a store isn't sufficiently profitable, they simply abandon it, contributing further to blight in the community they have cannibalized.