You can’t trust the police or the military either. The root cause of the current horrific violence seems to be that three cartels have declared war on the Zetas. The streets are beyond not safe. Cartels block intersections to hijack cars and rape women. The recent mass execution of those 72 migrants was not an outlier. Police stations are routinely attacked. The authorities are apparently powerless to stop it.
I say “apparently” because, as a long-time Mafia watcher in Chicago once remarked to me, some families are always getting arrested, other practically never. It’s not because one family is smarter. So, in part the authorities might not care much if a bunch of thugs kill each other saving them the trouble, it could also be they have a loose alliance with some of them.