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?
Spotify will force you to listen to an ad by pausing it if you mute the volume, then resuming it when you unmute.
I quit Spotify long ago so I don’t know if they still do it today, but they do have a way to force ads.
why do they care? they get their money anyways
I’m fairly certain any publisher could charge advertisers more money if they could prove the ads are being watched or listened to. And the advertisers would be happy with that.