In my cynical moments, I see this as a plot by rich transnationalists. That includes both wealthy Republicans and Democrats. To be brutally honest, this type of thing is good for the managerial/professional/political class. Non-English speaking Mexicans are not going to take away their jobs at Morgan Stanley. As an employer, it's a lot easier to mistreat an illiterate illegal from Chiapas than it is an American-born lower-middle-class person (they have guns, remember). Products and services become cheaper.
Hell, you can even let some of the brightest newcomers into the upper echelons of society. Helps to bring new blood into the Patrician classes.
The Roman Empire was like this, in its last days. The elites became even more rapacious, while the mob became even more useless to the Empire.
Meanwhile, the barbarians gathered over the Danube....
"In every country and in every age, the priest has been hostile to liberty. He is always in alliance with the despot..." -- Thomas Jefferson