severe labor shortages
i.e. not enough slaves
You are right on the mark.
Employers would have no trouble shutting down the border if they could get sued by someone under the RICO statutes for hiring these people in the first place. The next time an illegal alien kills someone in a drunk driving accident or somesuch thing, I’m going to point out that the victim’s family might be able to seek compensation from the employer under these statutes in the hopes that it would catch on. If this did catch on, would see such a swift backlash against illegal immigration that no employer would go near these people and they’ll all simply want to go back home.