Verstehe verstehe...
I understand that they come to live a good life. Don't we all? But the problem resides in keeping everything stable for everyone else as well. Illegals do pay sales tax, but they aren't even recorded by the government as employed, so they don't get taxed. However, they still benefit from them.
Ah well, I guess I should put it another way, as in my edited post:
"Edit: I have a very strong opinion on this - however, what I am trying to suggest is that illegals, rather than continue their lives as illegals, try to become legal immigrants. Either that, or cross legally in the first place. I have absolutely no problem with legal immigrants, or those who try to get their hands on a green card. "
There are those who try and have an honest effort. And then there are those who want to get a free ride. I feel that your parents are most likely the former, it's just that they're having difficulty getting past all the crap.