re: Mexicans in the US sending money back home
I don’t know for sure, and am too lazy to look it up, but I would be you dollars to donuts that the money being sent back from the US is biggest single cash cow for Mexico. I would also think that a lot more is sent back than we know about. Add to that the money made from the drug trade and it surely makes it the biggest component of their economy.
Drugs, remittances, tourism and oil are the four pillars of the Mexican economy.