Personally I find these kinds of things fascinating. Partially for the practical problem it represents and it's facets but also the one sided backlash of it all. Moderation is an interesting conglomerate of so many factors.
First of all I don't think Meta is a good or honest company, but that doesn't mean they're not trying at all. In reality even if they were good and honest I genuinely believe their task is probably nearly impossible. Humans just suck too much. It certainly doesn't help that Meta has at least some perverse incentive to be permissive with ads, as they get money from them. Though Meta execs aren't stupid. Inflammatory political ads are one thing, kiddie porn is another I suspect they lose more money over CSAM than all the ad revenue from them. I believe them when they say they removed over 36 million pieces of child sexual exploitation content last year.
Which is a number that I should let sink in. Basically more than one piece of CSAM shows up in their ad stream every second of every day all year. If their moderation techniques are 99% effective that results in 360,000 CSAM ads leaking to the public annually.
Another interesting thought is how much would it cost to actually get that rate to 100%? let's assume human moderators aren't paid much but are infallible. That all-in a single moderator employee costs $65K , that's salary, benefits, HR ratio, psychological therapy, equipment, the works, all factored in.
let's say on average you get about 1 ad review ~every 2 minutes, so bout 250 ads per-day per-employee factoring in some time off you actually get about 65,000 reviews a year. So bout $1 per review. So the question begs how many distinct ads enter their system each year? which I haven't found a stat for. But assuming only 1 in 1000 ads are CSAM, which still feels high but is probably a reasonable ratio. we get 36 billion ads needing review annually. At a dollar each 23% of their gross annual ad revenue each year would be just moderation overhead and they would need to hire over 550,000 moderators.
Evil or not I think they organically built a thing that operates at an unimaginable scale, that even moderation with failures in the parts-per-million would result in tens of thousands of unsavory or unscrupulous ads reaching users and they have neither the incentive nor the capacity to reach even that level of accuracy.