To clarify some points:

-Only Mexican citizens "BORN" in the country and/or anyone from parents "Born" in Mexico (Either Father, Mother, or both), can legally fly a Mexican registered airplane for commercial purposes.

It's called "Mexicano Por Naciemiento" in Spanish, and it's in the 30th or
32nd article of the mexican constitution. One of these states what constitutes "Mexican by birth." criteria.

There are lots of "N" registered aircraft in Mexico, so even if you can't find a job flying for an airline, check some corporate depts. out..