I was recently the victim of an attempted mugging, while walking. This occured on a busy road with dozens of cars driving by in the short time this took to happen, but with no other pedestrians around. No car stopped, no driver offered any assistance. I am convinced that, instead of cars, if cyclists or pedestrians were going by, someone would have helped me (even just by calling the police).
I've cycled for years, and gotten all the physical abuse, verbal abuse, horn-blowing, being cut-off, etc. that goes with it. I think a lot of drivers really aren't functioning members of society when they get in their car. They're in their own little world, not connected with reality.