H1B visas have provisions which require a worker to leave the country if they lose their job and don't find a new one within 60 days. This is probably the best-known such status on stackoverflow, but I am sure other guest-worker visas have similar provisions.
This creates a situation in which any boss has the power to coerce workers, on such visas, to accept work conditions which a person would not accept if the only punishment for disobedience would be getting fired. It does after all give bosses the power to threaten workers with being uprooted (and face a potential deportation).
Has there been any legal challenge to this program based on the equal protection clause? After all, coercive powers which this worker status grants to bosses may, from time to time, deny workers protections under labor laws (or at least make such protections much more difficult to enforce).
If no such challenge has occurred to this day, who could potentially have a standing to bring it to court?
Just to preempt any objections that constitutional protections apply only to citizens, the Constitution makes a clear distinction between which rights belong to citizens and which belong to "persons" (a broader group) within the bounds of the jurisdiction. The equal protection belongs to all persons:
XIV.1 ... No state shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States; nor shall any state deprive any person of life, liberty, or property, without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws.