People cut off anything: semis, other cars and motorcycles. Just oblivious and rude. I try not to switch lanes until I can see the car I've passed in the middle of my mirror but others are not as nice.
I have noticed one thing that irritates me about semis though and it happens enough that I take note. I cruise about 5 - 10 miles over the speed limit on the interstate so I tend to roll with or slightly faster than other automobile traffic and pass quite a few semis. One thing that irritates me is to catch up to two semis, I'll be the only car in sight behind the trucks but as I get to the point when I'm a truck and trailer length behind the 2nd semi will cut me off and then proceed to tool along at a speed only slightly faster than the semi it is attempting to pass. Am I receiving their angst from being cut off earlier or do they not use their mirrors and see me?
Trucks have to pass whenever they get the chance. They also can't ride bumper to bumper with other vehicles. So when a gap opens that they can fit into to get out from behind a slower truck, they take it. They would pass more quickly, but most trucks have speed governors and truck speeding tickets cost more and have more repercussions than those for regular cars.
