It's only breaking rules that the local governments allow it to break.  The unfair labor practices are unfair, only in the case of illegal immigrants being hired illegally.  Otherwise, the workers do not have to take the jobs.  There may not be any others jobs left, and so the worker will make his/her decision.  But there's nothing unfair or illegal about this.  Wal-Mart is simply capitalizing on a soft labor market and a demand for its jobs.  This is a textbook concept.

It forces suppliers to set prices extremely low, but that, too, is not unfair.  The suppliers don't have to put their goods on Wal-Mart's shelves.  They may go out of business if they do not, but, again, that's a choice they must make.  What you call unfair is really the way in which the system is supposed to work.  Wal-Mart needs to keep its prices low to remain the leader in the sector, so they push suppliers to keep prices low.

Similar arguments have been made about Home Depot, in the past.  But, here again, Home Depot must now compete with Lowe's and, to a lesser extent, Ace Hardware.  (Ace has smaller stores, so you pay a premium for the company not taking advantage of economies of scale.  But you also pay that premium for convenience, since the stores are often closer to people's homes.  CVS and Wal-Mart would probably be a decent comparison.)  Home Depot is notorious for beating up on suppliers, and yet the suppliers stay and we enjoy lower prices for wood (which is critical in my state during hurricane season, as anyone, who watches the news, knows).

Be nice to America. Or we'll bring democracy to your country.