I got my motorcycle license so that I could split lanes when I lived in California. It's legal in the sense that there's no mention of it in the books. So you can split lanes as long as you're not being reckless. Some car drivers had a problem with it and when they saw you coming up behind them they'd move into your space to block you. Bizarre.
I thought this was just a thing until I moved from Cal to Arizona and people would get really mad about it until I asked someone at work and learned it's illegal.
> Bizarre.
It's because they feel you're creating a dangerous situation for everyone around you for your own convenience and disregard for others.