Last summer we experienced two cases of absolutely terrible driving. The first was were a driver kept speeding up then slowing down to block me from merging. The other was a person driving a very large (3 axle) fifth wheel on a one ton dually blowing by everyone doing at lease 75 in the fast lane when we had a 40 mph wind quartering us from the front. I told my wife that we would probably see him again. Up ahead we came to a traffic slowdown/(stop and go) that lasted about a half hour. That 5th wheel/truck unit was in the ditch and looked like a bomb went off in it. Unfortunately both people in the truck died.
So, it is not always "the other guys" that cause problems.