I'm Mexican, and this results baffles me too. I would say that maybe current perception of government corruption (which has been declining for years and is really really low) has a lot to do, since many people might feel that Mexican society is in debt with them because of the poor perception we have against the current state of affairs.

Also I wonder if this was done in big cities like Mexico City (my guess) or more evenly distributed. I have a perception that Mexican society in general is pretty honest, but big cities are more rootless and impersonal. But this didn't seem to apply to India or other high density countries.