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?
because Spotify has no real competition, the music mafia has no reason to change their business model, and people are less tolerant of ads in their music.