Again, nothing except photos you uploaded to iCloud was to be scanned.

Apple's plan was to have your device conduct the scan and encrypt the scan results so not even they could see them until a threshold of ~30 image matches was reached.

This protects the user from false positives.

Once the 30 image threshold was crossed, the plan was to have a human review before turning someone into the authorities.

I think we all know that Google is not ever going to hire expensive human beings to supervise it's algorithms, so a single false positive would likely see you turned in for kiddie porn.