I wish everyone could experience the rural southern border areas. It's ridiculous how much stuff is required because there is no barrier. There are millions of dollars of highest tech detection gizmos deployed all over the desert. Along the east west regular highways, every day they groom a sand road smooth, in order to be able to see footprints crossing it. There are border patrol trucks all over the place. There are numerous mandatory checkpoint stops of all vehicles, wherein they question you about your citizenship. One time we were in Las Cruces with my wife's part Cuban cousin and his Mexican-American wife who live there, and we ran into one of those checkpoints on a town street. It feels like some German movie thing, "Papers, your papers please!" This is in America, 50 miles from the border.
I despise the checkpoints, and my wife dreads it when we approach one because she thinks I'm going to do something that will get us cuffed and held at gunpoint. 🙂
I don't know if a barrier will work. But, I can tell you that the existing stuff doesn't work well enough, and the area within 50 miles of the border feels like some kind of endless military state.