iirc meta on its own spends billions on content moderation, much more than other companies generally do. the problem is with content moderation, you only see the stuff they miss and not the stuff they already filtered out.
on the topic of weeding out CSAM, an example of where a company gave up on it is nintendo suprisingly. when they had flipnote(a 3ds application where you can send post it nores to others) was used by predators in japan to lure children. Nintendo deemed it not moderatable and since then, removed. flipnote and no chat replacement has since then replaced it functionally.
moderation is super tough and you can hear some really fucked up stories these people go through, even ones who have to go through more content (e.g people who have to filter out content in china due to government surveillance) has and how it affevted their lives.