> obviously they will not mind Apple scanning their photos to prevent horrific crimes
But Apple scanning all phones for CSAM makes it look like you're guilty unless proven otherwise. It's not even about preventing crimes -- Apple will only flag your device if it has a photo from the CSAM database. In that sense, the most horrific part of the crime, i.e., the abuse of a child, has happened already.
All the other major services already scan your photos with similar algorithms, the only difference is that apple is trying to do it in a much more robust and privacy preserving way.
But Apple scanning all phones for CSAM makes it look like you're guilty unless proven otherwise. It's not even about preventing crimes -- Apple will only flag your device if it has a photo from the CSAM database. In that sense, the most horrific part of the crime, i.e., the abuse of a child, has happened already.