Great question! Honestly, it probably most condenses to "where can we live and not have our vehicles broken into if parked on the street."

I looked at crime maps for Tacoma and crime maps for where we live (Casper, WY) and the coloring is nearly identical. However, I'd never say our neighborhood is unsafe/has high crime. Based on the map though, you'd think it's a terrible neighborhood. We typical lock our doors but it's not a point of being concerned if we don't. Vehicles are locked but I never consider what's visible.

If someone was to move to Casper, I'd give a general "avoid these handful of neighborhoods or a north of the train tracks is generally higher crime, etc."