If someone behind you is going faster than you, you should move to the right lane as soon as you can safely do so without slowing down or cutting anyone off. If it means speeding up a few MPH for a few seconds, just do it. If you do this, no one will ever have a problem with you, and you’re much less likely to be…

It’s because there are people blocking the left lane(s) who shouldn’t be there, forcing people to try and pass on the right. You’re describing yet another ill-effect caused by idiots who drive slowly in the left lane.

And then there’s a traffic jam and everyone gets a ticket