I'm not sure on what Trump's Great Wall accomplishes that the existing steel barrier does not. You can't drive through either, though you can drive through the hundreds of miles with no fence at all. You can scale either one. You can put a ladder up and let people down the US side with a rope. That seems like either one is very easily defeated.

In fact, the comb-like steel slats could be opened with a 24 inch gap with one small thermite charge. Put a few cardboard boxes around it and nobody would notice. That's just made from aluminum powder and rust, so it's available to pretty much anybody who wants to melt some steel.

You can also tunnel underneath, which has been done for decades. But really, most undocumented people came here with a legitimate visa, and just overstayed. What is a wall supposed to do about them?