Slow Drivers In The Passing Lane

Remember when people had the brains to drive in the left lane only when they were passing?  Nowadays, it seems people just don't care about any other drivers but themselves.  They get into the left lane and stay there, because they don't want to be bothered with changing lanes.  This causes many collisions on the highway, due to people in the right lane moving to the middle lane to pass, and people in the left lane having to move to the middle lane because some dimwit won't move over and is impeding traffic.  Arizona has signs that read "Slower traffic keep right", but apparently they don't have the wisdom to know what that means.  I believe Arizona should adopt signs like Colorado has, "Keep right except to pass" for their highways.  Otherwise, MOVE OVER PEOPLE!!