*I say "perceived safety," because vibes seem to matter more than actual safety. Like, the stats on car wrecks, drunk driving, distracted driving, and so on are alarming. But when I think of someone concerned about "safety," I imagine someone being uncomfortable around people they feel are sketchy.
I think an interesting thing to remember about perceived safety, statistical safety, and actual safety, is that they are all different things -- you can't just look at stats to determine actual safety.
E.g., I was involved in a couple of incidents involving attacks in SF that I am sure were not reflected in the stats. (As well as numerous thefts, though that's not a safety issue per se.)
Convenience is a big part of it, sure, but even Americans will use transit when it works for them, even if it is not faster (it is almost NEVER faster than driving a car unless you do strange restrictions or include a very-high-speed segment).
But you only need a few bad experiences on transit to put you off it when you have other options.
Spending time around degenerates degrades your life. It changes how you see people around you. It makes you see other people as threats first and people second.
Trauma is real too. Seeing someone nod out from being on drugs, or fights, or whatever else, puts you on edge.