https://en.wikipedia.org/wiki/Chinese_Student_Protection_Act...

In this case the automatic permanent resident status was created by a specific law; it wasn't a consequence of general legal principles.

The U.S. government does offer a relatively automatic asylum when people experience or fear certain kinds of persecution abroad, but the determination is supposed to be very individual and fact-intensive.

There was an exception to the detailed factual inquiry for Cubans: generally any Cuban who made it to the U.S. -- evading the U.S. Coast Guard, which was trying to prevent people from taking advantage of the policy -- would be given permanent resident status.

https://en.wikipedia.org/wiki/Wet_feet,_dry_feet_policy