There are rival gangs in Alaska and people killed over drug deals gone bad in Anchorage all the time. I said "exaggerated" because the drug cartel is not moving across the border and killing innocent people. It sounds like most of the killings were drug deals gone bad. The rancher being the exception, but like you said, he might have just shown up at the wrong place at the wrong time. It happens all over the US and involves US. Citizens killing each other more than foreign druggies running across the border and declaring war on us.
Now US citizens going to border towns, need to be on high alert, although the rest of Mexico is relatively safe, the usual precautions still need to be taken.
No, they force immigrants to become mules, and they are definitely waging a war on and near the border of Arizona killing agents and cops. I posted a few stories about it. Ignoring the issue and trying to say it isn't important because only a "few" have been murdered by the cartels in Arizona is ridiculous.
And this simply ignores and says nothing about other significant issues with illegal immigration within Arizona.