If you commute into a busy town, you share the rods with hundreds or thousands of drivers every day. The vast majority will be perfectly fine, some may be a bit careless, but the 2 or 3 angry worthless road warriors really escalate the risk factor.
Back to the op, I knew a guy who had killed a child that ran out in front of him from behind a parked car, he was never able to drive again, and was even an awful passenger in the car.
He was driving like pretty much everyone does at 30mph, like most of us will. But I do wonder about the way we have prioritised our environment for cars. You see much more in Holland and Germany, many residential streets are effectively pedestrian zones where cars have secondary priority.