People don't know how a 4-way stop works, going 15 mph downtown, pulling right out in front of me, etc....

And let's not forget my personal favorite, the guy ahead of me going down the road, fully facing the back seat and fumbling around for something, dang near hitting parked cars because he's swerving all over the place, while going 17 mph in a 25 mph zone. If I'd had a gun, no jury would've convicted me, I'm sure.