[bzbarsky]

> but Apple has said that the scanning is done on-device

Yes, but only for images being uploaded to iCloud.

> meaning whether or not you upload your photo library to iCloud, your local photos will be scanned

Not in the currently proposed implementation, if I understand correctly.

Disclaimer: All my information about this thing is from news articles; I might be misunderstanding the details.

[vorpalhex]

So child molestors will disable iCloud upload and innocent people will have their privacy violated?

[bzbarsky]

That is one plausible outcome here, yes.