>Who is it that is going to decide how much profit is enough? The government?

Walmart is deciding that now, because most of the government controls on corporate power have been neutered and corporate tax rates have been reduced to almost nothing by loopholes and offshore entities.
Who is the "Walmart" who is deciding that?
Walmart is now controlled by the children of Sam Walton.
Sam was quite a fella, for sure, but his kids?
We'll never know what they might have done on their own, but the chances are they won't be waiting in those long lines at Walmart very often as they decide how much profit is enough, and the chances are that their health coverage was a bit better than that of most of their employees as they decried the outrageous excesses of Obamacare.

The Waltons (not the TV family) and people like them now basically own both political parties, so it really doesn't make much difference whether they decide or the government decides.

That is not cast in stone, though. Obama reneged on his promise to change that trend, but change will come.