You live in a different world than me. Around here, there are many, many times where cars are stacked up behind people going under the speed limit ... and it's definitely not restricted to just RVs and big rigs. Few people are doing 10-20 mph over the speed limit where I live (or have ever lived). 5-10 is much more common.
Single lane (in each direction) travel is pretty clear: move over when safe.
Multiple lane (in each direction) is also pretty clear: stay right unless you're passing.
Here is a collection of "Stay Right" laws compiled by MIT with links. A lot of this is summarized well in
the Wikipedia page about lane travel.
Finally, here is a good infographic:
There are two keys here to remember:
- Your speed doesn't matter. 5 mph under, exactly the speed limit, 5 mph over, etc. Irrelevant. If you're not actively passing someone, move right. Period. This is the same for semis, RVs, passenger cars, horse and buggy, etc.
- What the other guy does is not your concern. You're not moving over "to let others speed." Don't worry about the others. Worry about yourself. The law dictates you move over, so move over. What "the others" do isn't your concern. You are not endowed with the responsibilty or authority to prevent what you may perceive to be their bad behavior. If you want to to that, get a job in law enforcement.
For those in the "I'm not moving over if I'm doing the speed limit" camp, just be aware that the law doesn't agree with you.
This Colorado State brochure does a good job of explaining how these Move Right laws help balance reasonable speed with traffic flow.
South Dakota is the only state that, in contradiction to the federal Uniform Vehicle Code, allows people to travel in whatever lane at whatever speed. Seems like a lot of you would be happier driving in SD.