Maybe for the very shameful way the elite upper classes treat your mestisos and indians. The vast wealth of Mexico is only for a few --- you know that. Although Mexico competes with Great Britain in number of billionaires, you have a very shameful system that denies the majority any access to education --- maybe some crappy unheated school if they're poor --- and medical care for the mestisos and indians? That's a joke.
The really sad thing about your country --- although you seem to be just fine with the injustice there --- is that many of those campesinos actually can make in the USA --- but they can never make it in their own country.
I know of no Mexican at all who believes Americans are killing the girls in Juarez --- most Americans never go there anymore. Most of the poor families believe it is the sons of the wealthy --- which is why they're protected and your government isn't interested in solving these murders. Or the police themselves or the drug cartels. The poor in Juarez don't believe it's Americans ---although the elites would like to convince them of that. Shift the blame obviously.