In my place, there's a significant group of drivers who will ride your tail too close hoping you'll move over so they can get 1 car ahead. And if they see more than 0.9 car length in front of you they will do what they can (weaving other lanes) to try and get into that space, 1 car ahead of you.

As far as I can tell it's pure selfishness and competitiveness. Their desire isn't to cooperate and arrive it's to take from others for their own gain.

Also "Only pass in the left lane" only makes sense when the lanes aren't significantly full. The guy in the left lane wants to do 90mph but the average speed of traffic is <55mph. Should I move over just because I'm doing 55 (despite wanting to do 65) and they want to do 90? They can only do 90 if there's a cascading group of drivers in front of them who defer their own desires to the desire of the most aggressive. Seems obvious to me that moving over to let them pass is not the right move.