It really should be though — traffic in CA flows ridiculously poorly compared to everywhere else I’ve driven.
(Left lane fast, right lane slow is the law in many parts of the US, even though passing on the right is generally legal too.)
Not only do vehicles traveling "at a speed less than the normal speed of traffic moving in the same direction" have to keep right (CVC § 21654), there are often signs indicating this on the freeway.
I don't either. As long as they're not hogging the fast lane.
But I'm very mellow now. Many years ago, when I was stupidly talking SSRIs to treat bipolar depression, I was a total asshole. I didn't tailgate or whatever. I just drove like they were stationary obstacles.
And what's bizarre is that I didn't feel angry. More like amused. It was like a game. Albeit one with potentially fatal consequences.
Then I got off SSRIs, and stopped being such an asshole.
But to others, that would have been a subtle distinction.