But Mexican history evolves from the Spanish system of a few wealthy land owners and the rest surviving on what they are given or can snatch away from the rich.

"I've been down so goddamn long, it seems like up to me." :(

Which is what happens...
You just trade one corrupt regime for another. The US has never overthrown anyone and placed anyone better in their place.
It is better for them to do it themselves.

Spex was right though, these people can't think that far ahead because they have bigger problems in the here-and-now. When you're kids are crying because they haven't eaten today and one of them has an ear infection you can't have treated you aren't going to be planning your involvement in political movements. It's a dicy issue, we have the resources to help, but we can't do it on our own without the people we're helping rising to the occation. If they don't then we've wasted our time and effort. I don't think there's an easy real-world answer to this, but what is the least of all the evils?