Yeah this is something that bugs the hell out of me too. Especially the headlights at night thing that really gets me going. The part that annoys me the most is when they refuse to pass me. They're in such a hurry that they'll ride you for miles but they won't take the initiative to just go around.
Yep, that's a sure sign of somebody who just isn't paying attention to what they're doing. Speed up and they speed up, slow down and they slow down. They don't necessarily want to go faster, but they can't seem to manage following at a comfortable distance.