The BBFA and MPAA, if I understand correctly, watch every second of content they rate. They have a back-and-forth with creators when there are disputes. They can afford to communicate, well, this is one f-bomb too many and usless you remove it, it's an "R" rating.

Secondly, they work with (largely) mainstream content producers (e.g. movie studios), who rarely act with downright malicious intent because of reputation and money on the line.

I don't believe content moderation is a problem solved well anywhere.