Shame of America's migrant labour market

Today's Independent leads with a shocking tale of how migrant workers are abused in the US, and simply so we can pay less for our food (see here). I try to avoid foreign vegetables and fruit (with the exception of fruit you can't grow in this country) anyway, but isn't it time we all started asking questions about where our food came from and wondering why it's so cheap? Or are we really so self-serving we couldn't give a toss about the welfare of our fellow man, just so long as we squeeze a few more pennies out of our change at the checkout?