Several movie and TV sites have come and go where you can just visit and watch without even creating an account. Quality might not be as good as a paid service and they are no doubt in the grey-to-red zone legally. I don’t see the same service for music.
Why do you think is there such a difference in trends?
I’m not sure I understand. You can stream music for free on Spotify, Tidal, Deezer, Pandora, Bandcamp, YouTube, and probably several other services. Not to mention the thousands of radio stations you can stream. It seems like there are exponentially more music streaming options compared to video. If you’re asking about sites where you can stream without ads, I’m guessing those exist too, but I suspect most people are either willing to listen to ads or pay for ad-free with one of those services.
Or they use ublock origin.
uBO + YT background play add-on on Firefox Mobile is a game changer