Earlier quoted context omitted.
And what of the bias that says "every city that I deem 'unsafe' is indeed unsafe"?
You can look at the murder rate per 100k people and draw a conclusion, all without any bias.
I will say that I have felt more uncomfortable walking in certain parts of LA, NYC, Oakland, Chicago, and yes SF (I lived SOMA in early '90s, before the boom), than I have in Mexican cities. (Not minimizing the carnage, if you live outside of the nice parts, I'm sure it's hell.)