I can attest that the people there are very hard working, I think most US citizens have no idea. At least this is true for people who are lucky enough to end up as professionals at the many factories that are there. Of course there are still many poor.
One interesting theory I heard about the entire Latin world (explaining why it tends to be poor) is that the old Spanish empire was deliberately modeled to be an extension of aristocratic Roman empire. The problem that this causes is too much power in the hands of aristocrats, with not enough space left for risk-taking entrepreneurs. To the degree that this is true (I'm not sure..), longstanding contact with the US may moderate it in Mexico in particular. Here is a video about it: