It's a stupid boondoggle.
[ladders]
Walls do not reduce transit to 0%. But they do cut it down a lot. Which is why lots of places (airports, Vatican, rich people's houses, etc.) use walls. When Hungary put up fencing across their border, crossing went from 4000-8000 illegal immigrations per day to a few.
But the vast majority of that mileage can be easily be covered with remote sensors and drones
That is excellent. But it requires government agencies to do or be allowed to it. Lots of people are concerned that an administration could have all that stuff stand down and do nothing.
You want to fix illegal immigration? Throw a couple of hundred rich factory\food processing executives in prison for employing illegal labor. 95% of the problem would disappear immediately. Problem is, those are probably Republican donors.
Yep. But they are democrat and republican donors. They are what people on both sides call "establishment" -- folks who utilize connections to government to get more money.
Also, I think there are political incentives that can favor illegal immigration.