So what if a small circle of people produce their CSAM material by themselves and share only among themselves? None of the pictures is being uploaded to that database, so either the algorithms are really really good at recognizing them, or it will require human intervention, that is, scanning one by one all phones, then deciding which picture matches the criteria and write down the names of the people involved. I can't think of a similar scenario that doesn't imply the total loss of privacy by anyone even remotely linked to one of these people.