There was this little known case where the Pharmaceutical industry sued the USA and CBP when they closed the border to Mexicans coming over to sell their plasma. CBP lost www.propublica.org/article/us-b....

Judge Lifts U.S. Ban on Mexicans Entering Country to Sell Blood Plasma

Mexicans with short-term visas comprised as much as 10% of all plasma collected in the U.S when the practice was banned last year. Now, a federal judge has granted a preliminary injunction.

so they let them in to "sell plasma"—an obviously base form of exploitation—but any pathways to emigration, including economic migration or refugeeship, remain blocked? Very hard to frame that as a good outcome.