the trade unions just dont want to see those poor Mexicans being exploited!
That is indeed the arguement that left-wing people in favor of restricting immigration have put foreward: we must illegalize these jobs because the immigrants are being exploited (my first thought is that the immigrants want those jobs, so they are essentially going against the will of the immigrants themselves; you cannot claim to be "helping" someone by denying them what they want; in this case, jobs). They try to justify anti-immigration legislation (protectionism, and yes, I will continue to call it protectionism) by argueing on the basis of class warfare. Because, surely, being unemployed is going to put them in a better economic situation than being paid below the minimum wage? Not!
Ah, the logic of it is so wonderful! Let's help people by illegalizing their employment contracts!
My group blog: http://polycentricorder.blogspot.com/
"The fact that I have no remedy for all the sorrows of the world is no reason for my accepting yours. It simply supports the strong probability that yours is a fake." -- H.L. Mencken