In many cases, it's slavery (immigrants whose documents have been taken away). Occasionally, you have tragedies occur, like the Kenyan woman who received 3rd degree burns over most of her body, and her family didn't know until she was shipped back home to die.
Extreme, but is that what we're aspiring to?
But then, it would be incorrect of me to say that I'm making a purely economic argument because I've clearly moved into making a value judgment. I think that's still valid though. Do we want to live in a country where wealthy people - or even just the well-off top half/three-fifths/whatever - expect never to have to clean up after themselves? We don't even have to ask what kind of society that creates, it's in our national memory.
