Cartels power is certainly a result of disarmed Mexicans, the populace there is at the total mercy of their govt or any armed faction. If they arm themselves and defend themselves, the govt attacks them. If they do not, cartels or corrupt govt attacks them. It is a lose-lose no matter how you slice it.

There have been plenty of armed groups who used to terrorize the USA out in the badlands in the history of the country. Typically they were resisted and put an end to by local law enforcement calling up a militia to deal with them. Known most often as a "posse". Even where this did not put a direct end to a criminal or corrupt enterprise - the threat was always there, which attenuated large scale criminal behavior. The knowledge that committing an atrocity would lead to a large portion of the local population grabbing their rifles and coming for you was in fact the only real deterrent in many areas for many generations.

Of course thats not the whole story, as the US FedGov has extensive contacts and deals with various cartels - in addition to infiltration by undercover agents. Utilizing at times both carrot and stick, the FedGov does play a large role in keeping cartel violence mostly out of the USA - at least on a large scale.

Still, if the good guys in Mexico were allowed their natural right to arm themselves the situation would be much different. Today the impetus behind the rampant criminality is drugs... but it could be anything. The fact that a disarmed population is nothing but prey to whichever armed gang decides to victimize it, whether those armed gangs wear badges or balaclavas, will never change.

For who could be free when every other man's humour might domineer over him? - John Locke (2nd Treatise, sect 57)