> It is certainly not perfect

That's an understatement.

> controls on who can obtain passports are sadly the norm in the entire world

These restrictions are far from "the norm in the entire world".

Actually, not granting passports to people that are in dire need economically is fairly common, South Korea does it for example and so do a few African countries. Crucially it's not as bad as the previous system because you know of this complication before you make the choice of studying for these professions. It really sucks, but sadly it's more common than it should be.

> fairly common, South Korea does it for example and so do a few African countries

Source? To prevent goalpost-moving, the restrictions we're referring to are:

The government will protect "human capital" in its decision-making, and travel can be denied for "national security reasons." Those deemed necessary to the Cuba socialist revolution — professionals such as doctors, scientists and engineers — can be prevented from departing.