You can't have CSAM of a child whose pictures were never uploaded to the internet. Post hoc measures are a law enforcement delusion, more of an aestheticization of a solution than a solution itself. The money they fruitlessly spend on establishing a surveillance apparatus could've been much better spent on programs teaching people about digital literacy and how to be a proper parent. Saying an anonymous file sharing system enables CSAM is equivalent to saying the existence of a printing press enables libel