You mean they want to build a wall which is super expensive because it is supposed to be a miracle solution to immigration.... yet... they don't know how many cross the border that way?This is only due to the actual documentation of visa's. There's a paper trail to people overstaying their visa's. There's no paper trail or concrete statistics on actual people smuggling and illegal border crossing. To use the visa statistic, you'd have to get a more realistic statistic on border jumping but unfortunately the US doesn't know how many are actually getting across undetected.
Sounds like something wise to do