1. I live in the SE USA, where LE response may be anywhere from 1 minute to 1 hour.
2. Nastiness is popping up all over. Fast food restaurants, convenience stores, the neighborhood, even an eyeglass shop in the mall.
3. There are just some mean, evil ba$tards out there who don't give a rip for another human life.
I'll think of a few other reasons later, but for now, those will do.