Monty Python could not do justice to the screamingly funny remark about “bringing all the Mexican citizens back home”.
If Mexico itself underwent the very real and necessary reforms to turn themselves into a modern republic,, the Mexican “expatriates” would SWARM back home, and maybe even a few dissident “American” anchor babies with them.
Mexico is just barely past a late feudal state, in that the titles have disappeared, but the Hidalgo mentality remains. Descended from nobility, these heirs to the massive land grants from the Spanish crown have never given up their status, and control Mexico with an iron hand even today. Private land holdings outside these huge estates is something of a rarity, and is more of the order of a “life estate” than of a heritable title to the land.
Plus, they have Napoleonic Law - ‘guilty until proven otherwise.’ It is not Rule of Law there, but rather bribes are the way to get things done. etc.