Back in 2000, I lived in Saltillo Mexico as a salesman, traveled all over the country. My first few weekend getaways in Cozumel, I don't remember any "security".
Driving around Saltillo and other inland parts of the country though, you'd see a red flag of some sort on the side of the road - it was a military checkpoint. Spooky only in that all the military guys were basically young kids, from facial features, they were mostly from deep southern states. All carrying what looked like M1 carbines, no automatic weapons at all. I was probably stopped 10-15 times over the year, never a problem - the kids would joke around and laugh once you got thru the initial who you are what your doing thing.
Mexico City was another story - everywhere. If there wasn't an armed guard, there was a dog the size of a small cow. Back then, they were robbing people at stoplights in the backseat of the old VW's. We always stayed in Zona Presidential and had a private driver - at dinner, there'd be military guys out on the streets but again, no automatic weapons.
State cops and local cops were all unarmed, federalies driving the black cars were armed and I was warned not to offer them bribes - any other officer, bribes were a way of life.
Times were way different back then. The guys you see now all have automatics, but they're older and look way more trained then back in the day. I don't know that I've ever seen one not smile back at you or nod - standing out in the blazing heat in all black. Just what there job is, what it could mean, I have a lot of respect for those guys - they don't bother me at all and it ain't bad seein