I have come to think this is coming from a certain righteous attitude. Everyone knows about the old norm of slower traffic to the right, but people give up on it when 1) why should I get behind that guy in the right lane who is driving slower than the limit, just so you can speed and 2) if you want to speed, find your own way through traffic, not my problem. There's also the variant of, I'm speeding and people are getting out of my way, why should I get out of your way because you decided to drive even faster than me. It just encourages faster and faster driving. I live where it's very common to see anything from -10 to +30 the limit. Which is just dangerous. The safest thing to do, is to stay where you are and let the fast guy find his way through or be forced to slow down. So I do kind of agree with this being an outdated norm that doesn't apply to today.
What you're taught in driver ed means nothing after a little time on the road dealing with the norms of other drivers and the inconveniences they impose on you. Nobody wants to be inconvenienced any more, even if it's the "right thing" to do.
Some what related, I feel I notice in last 10-20 years people absolutely refuse to miss their turn/exit. They will create a very dangerous situation swerving across lanes and cutting people off at the last second rather than saying "oh dang, I will need to do a U-turn ahead".
Another example I notice is, the use of a turn signal is an expectation of the right to change lanes. People actually get angry with thoughts like "I put on my turn signal, everyone else should slam on their brakes so I can change lanes because I need to turn now!"
