I agree that this is probably the predominant factor. Even with my own life, many of my friends and coworkers think I am risking my life somehow when I ride the bus and train in to work. I'm like, have you actually ridden the thing? Sure there are a couple drug addicts and transients but the majority of the riders are just people trying to get across town and I've never once felt unsafe. But try and explain this and its like they refuse to value your actual lived experience in favor of the fear they have bit into hook line and sinker.