I don't think I really expect people to stop shopping at places like that. I'm just surprised that most people can't link their purchasing choices to some of the bad things happening in the world. They will buy the cheapest piece of clothing and then claim outrage over child labour, they will buy non sustainably bought fish and cry about dolphins dying in dragnets in nets and so on and so on.
Again, I'm not surprised these "bad" things happen. It's inevitable. It's that people manage to disassociate themselves from it as if they were wholly innocent. The correct response to this (to me) is to consider my purchasing habits etc and see how I can affect change with my pocket or vote, not to vilify Walmart and Amazon for being efficicient.
And yes, I think the answer to a lot of this stuff is legislation because otherwise people without scruples will always do something dangerous or unethical etc to make a buck.