Wow. Could that statement have been any more racist? People like you act like the person looking to exchange an honest days work to feed themselves and their families are Al Qaeda terrorists looking to kill you and your family. Get some perspective! Yes, the immigration system is broken but, they're not bad people (most of the time).
The people, not all Mexican, standing outside Home Depot, etc are just looking to make a living. If you hire them, you know what you are getting: uninsured, likely unskilled labor at cut rates. If it isn't done right... well, you knew what you were getting into. If it needs to be done right, get a licensed contractor in good standing.