My cousin's husband has been mugged three times in his life. Each time was when he was walking to school in NYC, each time was with a deadly weapon, and each time there was a chance he could have died. I've never heard of a single person being mugged driving to school.
I'm not saying this is the primary reason to have cars and live in the suburbs, but not being forced to share space with every random person in your vicinity is no small thing.