YT wasn't very sad about stolen content when they were starting up...
I’m referring more to the sheer volume of back catalog older/indie music that users have digitized from vinyl. I’ve talked to several indie label managers who gave up years ago trying to monetize/fight youtube with c&d letters.
There are tons of whole albums which are definitively not "monetized" by their makers.
E.g. old stuff where the band does not exists anymore or all the low selling genres where nobody cares. It is not a bad thing since i discovered a lot of cool stuff like that.
A breakdown of how the system works (they're trying to sell music for you to use, but it's still a good writeup):
https://www.safemusiclist.com/can-use-copyrighted-music-yout...
It's a clearly a consequence of Youtube being owned by a tech giant and having such a high profile, all the right holders are willing to tell their lawyers to pull the trigger if they find their content hosted illegally on Youtube. It's probably easier and cheaper for Google to be proactive about it than dealing with the probably tremendous amount of complaints that would be generated if they waited for right holders to make a move.
If you can steal from Disney, Youtube doesn't care. And no these videos are not being monetized by the creator.
How do you know that?
It may or it may not; I fail to see how that test would lead you to a conclusion here. You're making an assertion and really you have no idea.
The uploaders get through the filters with really strange editing tricks, cropping the screen and editing random bits together. It's not a level of quality that Disney would like to have associated with their brand in even the most unofficial way.
That they do, not wrong there.