I'm in a border state. Lived in San Diego for 30 years. You are right, no one wants to pay for social services for illegals. Heck, I don't want to pay for legals to have social services! But you cannot deny that $150 billion is a whole lot of labor that our gov't, of the People, is doing nothing to control. Your view of the situation is a tad simplistic.
The people favor the death penalty. But how many executions ever actually take place ? The people favor school prayer. But what chance is there of that ?
Elites can frustrate the will of the people. Elites who are interested in cheap labor and a left-leaning voting base.