Because it's easy and looks like 'progress' to people who live away from the border.
Yep. Interesting that being so far from the Mexican border you see it for what it is. More commonly, it seems, the farther folks are from the SW border the more rabid their position about a region most have never (perhaps will never) visit.
I live in Maine where there are miles of 'open border' in the forest and on the St. John River. Many folks come from Quebec and New Brunswick to work in the woods and farms each day and go home at night. It works, it's part of the economy and just like there, they are from families from BOTH sides of the 'border' The only difference is that they speak French not Spanish.
It's pure Mexaphobia.
Facts not lost on SW residents.