The idea of a wall is retarded.
Well, it worked in China. Oops, no it didn't.
How about Berlin. It didn't work there either.
Hey, well how about the places where we already have a barrier. Surely that has stopped some people...right?
The idea is retarded insofar as it is going to keep people out.
The necessity is that it limits payload (i.e. large amounts of drugs and large amounts of munitions).
But security isn't what it's about with trump enablers....the need to "stick it" to someone is the most important thing; always.