I've already stated this many times, I'll state it again. Get your shit out of YouTube and any other Google product. Google is a dumb, faceless, fully automated company only interested in extracting as much data as possible from its users, force them to swallow as many ads as possible, all without caring about listening to them (both consumers and creators), under the faulty assumption that they're too big for users…
And put your content where? What should this piano teacher do? This is partially the fault of YouTube/Google, but also copyright law in general. It's broken. This community, right here, could collaborate and force changes upon the powers that be. Boycotting Google and YouTube isn't going to do it though.
There's no legal grey area here. This is completely on Google/Youtube. Why isn't there a way to assert the copyright status when uploading, beyond saying you ownt he copyright or not? The answer would seem to be that it would take some work on the company's part, and they don't want to put it in because it's unlikely to yield any additional revenue and the occasional bit of bad publicity doesn't hurt them enough.