I can think of no other reason except maybe they themselves are crossing the border illegally back and forth for whatever purpose..
So much of the Texas Rio grande border is rocks, rattle snakes, scorpions scrub brush. Hotter than hell during the day and water is hard to come by. You can walk for days and never see civilization. Most border town residents live in poverty. Government subsidies. Lots of folks there love the isolation. Getting a fat payout from government will help out the small land owners. Not so much for the monster ranches though. Hope they sell quickly.