It is useful to understand the psychology afoot in drivers' behavior. For the inadequate personality, "moving over" feels like submission to someone else's will. As a defense the slow left-laner stubbornly refuses to submit, mumbling autistically to himself that he, by god, has a right to drive 55 mph in the left lane if he wants to. Much road rage springs from similar projections and imagined putdowns by generally oblivious strangers. As always, it is the loser who takes it as a personal affront when someone else just happens to want to pass.
I do it on purpose, with great deliberation. I know that I don't have a right to go 55, I have a REASON to go 55. And that is to piss off the person behind me.