Related to this - here's a scenario that happens to me almost daily. I'm in the left lane trying to pass a semi-truck. Mr. Important is behind me riding my bumper, obviously wanting to pass everyone. As I get past the trucker, with my right blinker on to try and signal to him that I am about to get out of his way , Mr. Important shoots over between me and the trucker and zooms past me, giving me a dirty look because I didn't move over quick enough.
My uncle was a long haul trucker. He said one of the most unsafe things people do while driving is cut off semi-trucks, or squat in front of them, so I always try to get ~3 car lengths ahead of them before I move back over.