A wall is pretty ineffectual unless it's manned round the clock, so even with drone technology etc, the construction costs will just be the start of some major on-going expenses for the US taxpayer.
Coming soon to a town near you:-
To make matters worse, south of the border, Mexicans are not entirely convinced that they should pay for it all. They are, after all, a proud and excitable people and I regret to say that of the ones I've asked, some have resorted to profane language to convey their lack of enthusiasm.
