Everyone misses the point....
The basic point is:
If there were not mexicans to be paid $3 an hour, they would have to pay legal workers minimum wage. Although this seems like it would make businesses go bankrupt it is BS. When more people are paid more money there is more purchasing power and it helps to grow the economy.
Paying mexicans $3 an hour and then having them send it back to mexico is called a capital outflow and it is only good if you are investing in a country with a higher real interest rate than your own. But they arent doing that. So we all get fucked.
There is also called the supply and demand of labor. If you raise the price paid for labor, your supply of labor will go up. No shit americans dont want to work for $3 an hour....
Now, if the companies paid the legal wage Im sure we could find many more americans to do these jobs.
Maybe it would pay off if some politicians were economists.