As I said, some of the music is just the audio of a video, but they also get a lot of releases directly from the publishers. They are both on YT Music and the difference in quality in between them is noticeable.
I have my audio quality set to high in that options menu btw.
The reason why I don't pay for a lot of media is because, if I pay for it I won't be able to watch what, when, where and how I want to.
If I could buy movies and TV series as h265 files with high bandwidth and no DRM I would pay for it.
I would also pay for streaming if it had all content available, no DRM that forces me to use Chrome to watch anything higher than 720p and a good interface.
But those things will never happen because executives are too greedy.