Because to truly moderate YouYube, you have to actually watch the videos, and YouTube says they get 500 hours of video uploaded every minute[1], it's pretty easy to estimate the staffing it would take each video once. They're basically getting 30,000 minutes of video every minute, so if they have 30,000 people watching it, 24/7, it basically works. You need 4.2 fourty hour weeks to cover a whole week, so 126,000 people will do it. They've also report 2 billion monthly users, so around 1:16k moderator:user would get full coverage of videos; plus another team for comments. And of course a team of 1/8th of a million won't manage itself, and you need an escalation path, and non-robot moderator are actually not robots, so they won't (and shouldn't) spend their entire worktime watching.

126,000 workers actually seems reasonable to find, the 2 million you'd need at a 1:1k ratio would be hard, I think. The pay is going to be bad, and the garbage you have to watch won't be worth it for most, but you still need a reasonably analytical person to decide if things definitely follow the rules, definitely don't follow the rules, or need to be escalated. And they need to be attentive, because videos can be totally normal and fine and then get abusive later.

[1] https://blog.youtube/news-and-events/youtube-at-15-my-person...