Because most are not breaking serious laws and the U.S. economy depends on cheap labor. Now, can you answer my question - you were the one who said "at all".
By "at all" I mean in a serious, substantive manner, as I believe you understand. But as usual you are quibbling.
What's a "serious law"? Do you mean as opposed to a law that you do not believe should be enforced?
I hope you know that you are taking an absolutely Clintonian philosophical position.