Are you saying humans cannot visually inspect the actual image that the flag is set against? If not, then how on earth do you prosecute someone if you can't demonstrate they had the actual image, and not just the derivation used to flag it?

The way I see it working is Apple scans a ton of shit, some of it shows up as possible child porn, human intervenes and looks at the source images, if there is indeed child porn they report to the police.