It’s possible that a human review system would be even worse. Have you seen the studies that show how insurance adjusters, working from the same inputs, with clear evaluation rules, have spreads of > 40% for the same case?
I find it highly unlikely that more than 1/8th of Alphabet's profits are coming from YT, so that'd make it a cost center... and I'm willing to bet it'd be deep deep in the red.
Because they don't want to pay for the manpower to manually review everything.
Youtube gets 250-300 million hours of video uploaded every year. At $20 an hour to review it, that's $6b. Call it $10b.
Alphabet made $86b last year.