What would you rather? Should Wal-Mart pay more for the labor of its employees than it is worth? Do you pay more for things you buy than they are worth? When you buy a car, do you tell the dealer, "Hey, I don't want your salesman to be poor, so I'm gonna give you $5,000 more for the car than you asked." I didn't think so.
The labor market is no different than any other market. In this case, the seller is the employee, offering his labor, experience, talent, etc. for sale. The employer is the customer buying that labor. Like any other sale, both parties are free to negotiate and accept or reject the deal. If the employer doesn't want to pay a particular price for a certain kind of labor, he doesn't have to. If the employee doesn't want to work for a particular wage, he doesn't have to.
If employees want to be paid more, they need to make themselves more valuable! Just like there are cars that are more valuable than others, for various reasons, there are also employees that are more valuable. Those who have more education, experience and/or skill than others will be paid more. Those who did not graduate high school, never attended college, and have skills that equal those of nearly everybody else, should expect to be paid less for their work. Why? Because there is a large supply of them.
It still comes down to supply and demand. There is a nearly endless supply of Wal-Mart-level people out there. That skill level is nearly like water. It's everywhere, so why should anybody be expected to pay a premium for it? On the other hand, if you are, as an example, an experienced, certified, educated and talented IBM AS/400 computer system expert, you will probably be paid handsomely for your work. Why? Because there aren't very many of those people around!
You make serious mistake - the labor is not a mere commodity - it the activity of the living human being, his life and soul is involved.
You sin against the dignity of man by treating him like a thing. And you sin against God in whose image men are created. Freemarketeers are at heart the atheists, and when they claim to be believers they are the hypocrites as well.