If you write, “In fact the only cities I’ve been to where I felt like I needed to really have my guard up and head on a swivel were US cities”, I wonder if you have ever been to, say, Argentina (Buenos Aires, Córdoba, Rosario), South Africa (Johannesburg, Durban, Cape Town), Peru (Lima), or Kenya (Nairobi). There it is one’s local contacts who encourage one to be vigilant and plan routes across the city carefully. The US has wacky urban safety issues, but it is just one member of a whole set of countries with urban safety issues.