The same principle applies though: Youtube has no say in deciding what is copyrighted or not. They don't want to have a say in it themselves. Someone, somewhere, claims that they own the copyright to x and y. Youtube can't and won't decide if that is truthful or not. Almost a decade ago, youtube gave the keys to claims to people to remove themselves from the equation. "Someone says they own this stuff so they took it down. Sort it out between yourselves."
How much would you bet that the same wouldn't happen to e.g. Warner Bros.. YT is quite definitely taking a stance, the problem is they're not taking a stance on truthfulness, but simply on how much money does it make us.
They are taking a stance on how much headache and money it will cost them, which is really reasonable. The reason old and unsustainable youtube died is because of the Warner Bros and alike - because their kind tend to hold an enormous amount of copyrights. If they feel they benefit from copyrights, then they will feel the most attacked. They, with their influence, said youtube cannot continue in this fashion back in the day, and it was true. They could sue youtube to the ground and they'd have to close down (assuming manual moderation is impossible). I am actually amazed that they allowed it to continue with this solution, being, "youtube, you give us the keys and we do the takedowns when we feel like our copyrights are violated, then you may continue" and youtube said "fine" and that is where we are. Now if you feel like your content is taken down unjustly, you should take it up with whoever is claiming ownership over your content. Which is... impractical actually, but that is how it is. This is one of the only ways within the current legal framework where you can have a site where people post content to freely without being liable for aiding and abetting copyright infringement yourself. No easy solution to this.
So yes, Warner Bros can be an enormous headache to youtube. Legally and financially. "Piano teacher" probably can't. Youtube acts accordingly which is pretty rational. If you owned a youtube-like service, you'd have to do the same.
I see where you’re coming from. But a class-action suit from nearly every user that has used public domain copyrighted material and couldn’t monetize it seems just as bad.
