There’s been a lot that has gone on with Mexico and the USA, not all of it pretty.
Whatever one’s views about drug legality, the clandestine traffic has been a terrible scourge to both sides of the border, and Mexico is even more ill positioned to deal with it than the USA is. The Wall will do Mexico a favor with respect to this, and make it less hellish.
A less hellish Mexico, in turn, will be less of a temptation to flee.
I remember Ciudad Juarez being a safe day trip for mom and the kids. I was fascinated by that rough iron VW Beetle on the streets there. Never a problem, in my childhood.
It’s a no go zone now.