Part of the reason why this was (and is) a terrible idea is how these companies operate and the cost and stigma of a false negative.
Companies don't want to employ people. People are annoying. They make annoying demands like wanting time off and having enough money to not be homeless or starving. AI should be a tool that enhances the productivity of a worker rather than replacing them.
Fully automated "safety" systems always get weaponized. This is really apparent on Tiktok where reporting users you don't like is clearly brigaded becasue a certain number of reports in a given period triggers automatic takedowns and bans regardless of assurances there is human review (there isn't). It's so incredibly obvious when you see a duet with a threatening video gets taken down while the original video doesn't (with reports showing "No violation").
Additionally, companies like to just ban your account with absolutely no explanation, accountability, right to review or right to appeal. Again, all those things would require employing people.
False positives can be incredibly damaging. Not only could this result in your account being banned (possibly with the loss of all your photos on something like iCloud/iPhotos) but it may get you in trouble with law enforcement.
Don't believe me? Hertz was falsely reported their cars being stolen [1], which created massive problems for those affected. In a better world, Hertz executives would be in prison for making false police reports (which, for you and me, is a crime) but that will never happen to executives.
It still requires human review to identify offending content. Mass shootings have been live streamed. No automatic system is going to be able to accurately differentiate between this and, say, a movie scene. I guarantee you any automated system will have similar problems differentiating between actual CSAM and, say, a child in the bath or at the beach.
These companies don't want to solve these problems. They simply want legal and PR cover for appearing to solve them, consequences be damned.
[1]: https://www.npr.org/2022/12/06/1140998674/hertz-false-accusa...