When I think of all the times in my 20s that I rode in cars driven by drunks -- or walked down dark streets with my mind 1000 miles away --
-- survived those without incident too but it doesn't mean they were a good idea or the next guy should do them.
I think "is it safe" can be good shorthand for "how risky is it, what will I gain if I do it anyway, and is the trade-off worth it?" -- assuming that if the answer is "yes, worth it" you still stay alert. But some absolute, set-it-and-forget-it "yes it's safe" or "no it's not safe" is less useful, especially in these rapidly changing times. The sense of safety you get from familiarity -- AND the sense of danger you get from unfamiliarity -- aren't always enough to go by. I used to visit Palomas about 10 years ago and see truckloads of scowling young men in uniform carrying long guns ... and get this warm fuzzy feeling because they reminded me of Berlin in the 1970s. Obviously NOT a cue you'd want to run with!
It's been a few weeks since we've had a plug here for Gavin de Becker's book
The Gift of Fear -- it's definitely a good resource on thinking through questions like this (in general, not specifically about Mexican border towns). I think it's normal for people to have different comfort levels for this stuff, but also a good idea to let ourselves be challenged to rethink them, in either direction, occasionally.
I loved the TV show Dead Like Me, in which one of the characters got dead by being hit by a toilet falling out of an airplane. Man plans, God laughs. But we still gotta plan sometimes.