Lucas, do you understand how hard it is to get a green card? Have you any idea of the expense involved?
It's not just a question of people not wanting to get a green card, it's a question of not being able to. There are fees upon fees upon fees; there are background checks and interviews to be conducted, and unless you have a pretty damn spectacular job waiting for you you are required to have a financial sponsor. So, it's not just as simple as filling in a form before you stroll across the border, it's MUCH more expensive and intricate a process than that.
And I never said that it WAS an excuse. Lucas seems to think that it's just a matter of filling in a few forms, and it's WAAAAAAAAY more complicated than that. My green card process took 4 months to complete and cost us hundrends of dollars, and that was back in 1994 before 9/11 happened. I shudder to think about how much harder and costlier it is now.
IG makes some very good points. Once they're here, it's difficult to make them leave - and if they've had children born here, those kids are US citizens. It's a mess, and there isn't an adequate solution in sight, IMO.