You have Mexico confused with Nicaragua circa 1970, I'm afraid.
I have traveled throughout Mexico, and most folks there have no problem with Americans as individuals, nor do they mind the dollars we spend there.
Oaxaca is a very volatile state, one which has been giving the PAN government hell for the past six years. Southern Mexico in general has seen tremendous social strife, as the economic gap between the largely Indian and rural south grows between the more prosperous (and mestizo) northern part of the country.
I’m not confused. I have traveled throughout Mexico since the early 70s; I was there as recently as last March when I made my fourth visit to the Copper Canyon at Divisadero Barrancas in the state of Chihuahua. And while I’ve never stopped to count the times I have heard that phrase I can safely estimate it to be well in the dozens. And yes, they do like our dollars. But they don’t like them enough to not show their disdain for the wealthy northern neighbors when given the chance.