Stereotypes aren't necessarily true. There's for example a stereotype about Mexicans being lazy, but anyone who's actually taken the time to look at the statistics - and gotten to know any number of Mexicans, for that matter - knows that to be a complete fabrication.
Lotta tech offshoring to Mexico these days over India, PI, etc. Perception is that the Indians generally get their skills through diploma mills while the Mexicans were generally more reliable and qualified. Better overlap with timezones -- Mexico City is on Central Time, and it's not hard to open a shop in Baja for Pacific Time -- and you also have access to the NAFTA TN Visa if you want to bring people across the border; no H1B visas headaches.
I seem to remember that one issue was that warmer climates had higher infestations of hookworms which manifests in ways that reinforce a "lazy and stupid" sterotype.
