You seem to be confused about what Apple is doing.
Nothing anywhere says that Apple scans the pictures you store on your own device. They only scan the pictures you upload to their cloud service.
The scanning is done on device before upload in Apple’s case, and in the cloud after upload in Google’s case, but either way it is only done to photos that are uploaded to their cloud services.
If you are really claiming Apple scans the photos you don’t upload to iCloud Photo Library, then you are lying or dissembling.
So it’s worse. They don’t wait until they’ve had several hits before they get any knowledge of it, they have a list of people who might have these images in their library.