I think Alfred Hitchcock would understand the "wall" isisue for what it really is.
A MacGuffin, a plot device, the audience really doesn't care about, to move the story forward.
Trump's wall, in the name of protecting the southern border, from a brown menace that really doesn't exist, is just his plot device for 2020.
Its the stuff Trump's dream are made of, except instead of a bejeweled black bird, Trumps are made of concrete and barbed wire.