Corporations rely on desperate, easily-exploited people in order to make obscene profits. There’s no way in hell they’d risk actually cutting off their supply of slaves, or else they might have to drop a couple of percent of profits on paying wages / benefits / etc.

The border laws aren’t intended to reduce the number of illegal immigrants, they’re there to make those same people more desperate and therefore more profitable, while at the same time stoking the enthusiasm of morons who will continue to vote for more pro-corporate politicians who will shovel even more money to the shareholders.