> when the basis is country-specific,

Not adjusting for population when the brunt of this policy is not borne by a country but a person, suggests malicious intent. All countries are treated equal, but all immigrants are not.

In theory, your argument sounds fair..

But in practice, is the US supposed to track down census numbers for the countries around the globe? So many countries, dont even have much of a process

and the main point is : the govt exists for the well-bein of its current citizens, not potential ones.