Also, you can not guarantee that apple/google will use only known instances of csam, what if, govt orders them/google to scan for other type of content under the hood, like documents or god knows what else bc govt want's to screw that person (for the sake of example let's suppose the targeted person is some journalist that discovered shady stuff and govt wants to put em in prison), bc you know, you don't have access to either algorithms and csam scan list that they are using, system could be abused and usually could means 'sometime' it will