I wouldn't say the corporations think about the benefits one way or another. They pay what they pay and mostly benefit in regions with low standards of living that have been abandoned by other industries. Wal-mart is a cannibal that mostly comes to pick on the dessicated corpse of once thriving conmunities. Locals can't resist the discounts and abandon local businesses because of their own depressed wages. Also because of the convenience of course.
The employees can attempt unionization or states and municipalities can regulate wages through minimum wage laws, but collective corporate power usually conspires against both. There is no free market competing for labor in regions like these, which cover vast swaths of the US and certainly the majority of the world. These are the consequences of the free market. Entitlements have a small distortion effect, but if they vanished, I'm not sure there wouldn't be Wal-Marts undercutting workers. We already see the digital version of Wal-Mart thriving in places like India and Pakistan with Amazon Mechanical Turk.
In an open border scenario, this Wal-Martification would likely spread like a cancer, though it already is online where there is next to no regulation of labor practices.