[The old Virtual Fence. Been there, done that. Or rather, didn’t do that, since it was just another excuse for maintaining the status quo.]
That can be turned off. You can’t turn off a wall.
I agree part of the effect of the wall is symbolic, in that it can’t easily be removed, but it will require defense just like a fence would. The best thing would be if we just got over our squeamishness about shooting border jumpers.