You just cited the best argument against the wall. Compared to the desert, as a barrier it is superfluous. That said, the difference between crossing the border near a port of entry and crossing the border out in the desert is not the quality of the barrier, it's the enforcement. Between Aqua Prieta and Antelope Wells it doesn't matter what sort of barrier you put up, I can come at it from the Mexico side with whatever equipment I need to get past it and no matter how hard that is and what equipment it takes it is a secondary cost compared to what I already need to get through the mountains to civilization on the US side. As it stands right now, I don't have to go terribly far from Antelope Wells, population two, to be able to cut through the fencing uninterrupted, but I still have the same problems.
What my somewhat tongue in cheek previous post was supposed to point out is that no matter what kind of speed bump you put out there, the only thing that would make a difference is building that thriving city, from scratch, at Antelope Wells that you would need to support the manpower to enforce the fence. Real time monitored surveillance of fifty miles of border, with personnel and equipment available that can deploy rapidly enough to at least keep your fence from being stolen is an ENORMOUS cost. If you have that, a chain link fence or even just a painted line on the ground will be fine. If you don't the ice wall from Game of Thrones isn't really going to stop anyone. Someone will just come along with a torch and take the time to melt a tunnel through it.