In the 1990's, I was hiring illegal immigrants. I didn't know that for sure, but I suspected. They had real-looking paperwork, and I was no expert on documentation, so they were hired. They worked their asses off, and I was glad for my decision. No one else was working at my side, for long days. Eveyone else would quit. These guys loved it.
Sometimes, one of them didn't show up for work. Hesitantly, the other guys would confess that he was illegal and that he had been captured in the night and shipped home. In the next sentence they usually assured me that they were not illegal. It was almost funny.
A few weeks later, that same guy would show up on my doorstep again looking for work. Sometimes as the same person...sometimes with new paperwork and a new name. I'd hire them back, because they were good workers and I took all the taxes out of their pay: so our government made out like bandits on these folks. They never filed for a reimbursement and they never used any of our American services - because they were afraid to get caught - and sent back.
The hispanic help played this game with our government everyday. It was just a fact of life and a cost of doing business. An expensive cat and mouse game that had zero net result - except to hurt our country on every front.
Then 9/11 happened.
After that, no one was interested in immigration. All resourses were directed towards terrorism. I actually called the I.N.S. once to report on a hispanic guy, who I learned was a bad actor (or "hombre", depending on your preference). Told the I.N.S. where he would be, and at what time, so they could pick him up. They told me that they weren't interested. That they were swamped with tracking down "terrorist" tips, and that I'd have to deal with it myself. Maybe that is why we see an increase in bad hispanic workers. The hombre I called about, went on to rape and molest a child.
So here's the thing: if you look at current reports about immigration, most suggest that more hispanics are actually leaving the U.S. now than are coming in. To me, that would make sense, as most of my guys told me that they only planned on working in the U.S. long enough to save money to take care of their families, so they could then move back to Mexico.
So it is my "somewhat expert" opinion on this, that THE WALL, is actually an lame answer to a problem that is almost 30 years old, and at least 10 years past being still a problem.
You are building an Edsel to combat a modern Honda Accord.
Totally a silly, expensive idea, that will be a monument to how government reacts to social problems typically decades after the people have already solved and moved past the problem.