The Mexican constitution clearly states that citizens have a right to own guns, as different from "arms" which they consider military weapons. The Mexican public, according to their constitution, should have the right to be able to walk into their own gun shops and buy handguns in any non-military caliber, shotguns of any sort, and rifles in any caliber under .30 cal, again, according to their own constitution.
What happened at some point is that a branch of their army was given a political/legal role roughly equivalent to our BATF, and uses their power to enforce "regulations" on gun ownership, and sort of like state owned liquor stores in Oregon, they are supposed to have government run gun shops, of which they have exactly one in Mexico city, to meet the letter of their constitutional obligation. That one shop, of course running limited hours of operation, an onerous licensing procedure, and limited merchandise.
So Mexicans, good or bad, for better or for worse, look to alternatives. Sort of like American teenagers given the choice between illegal dope or illegal alcohol.
Mexican officials should in reality be held to task for not just their lackluster history on civil rights, but their bold and blatant curtailment of rights clearly spelled out in their own constitution. Attacking that portion of our constitution that we have managed to do a slightly better job of defending makes this whole thing our business too.