Rudolfo Gomez won Tokyo and was second in NY in the early 80s. There was a lot more interest in distance running and other Olympic sports back in the 70s and 80s because of the rivalry with Cuba for Olympic medals. That has since faded considerably. But there are still a significant number of good runners from Mexico and South America. Juan Luis Barrios ran 2:10 in Tokyo. Jose Antonio Uribe ran 2:08 in Houston. Raul Pacheco from Peru is a 2:11 guy who won Mexico City.
Also, while there is plenty of poverty in Mexico, plenty of Mexicans do just fine and have good opportunities if they do well in school and go to university. And in Mexico, most everyone lives in very dense towns or cities. Streets are narrow and stuffed with cars and motorcycles. Agriculture is modernized. In the Rift Valley around Iten and Eldoret, a good portion of the population lives on small family farms. If you want to run, you just go out the door and run all you want.