YouTube is just incompetent
Right, watching and listening to 150 hours of new content uploaded every hour should be easy peasy.
Just imagine the cost of doing this. Imagine how problematic this is. The people forced/choosing to do this are subjecting themselves to abuse, at some point or continuously.
And how does one police/supervise the "reviewers"? Why, you need another person to listen to the same stuff to make sure, right?
Sounds like an impossible assignment to me.
The way I would handle it is to tell advertisers "You guys listen to the popular/monetized channels for us and if YOU find anything you don't like, let us know."
Notice how that doesn't involve Google?