They're willing to do things you're not willing to do.
Like violate this country's immigration laws, for example. Otherwise, I'll do whatever they're doing, for the right price. They're just willing to work more cheaply than I. And the net effect of that is to import poverty and widen the income gap in this country. Does it give you a warm fuzzy feeling to know you're on the same side as ConAgra and Wal-Mart?
"The fundamental principle of science, the definition almost, is this: the sole test of the validity of any idea is experiment." -- Richard P. Feynman