[altitudinous]

This article focusses too much on the individual case, and not enough on the fact that Apple will need multiple matches to report someone. Images would normally be distributed in sets I suspect, so it is going to be easy to detect when someone is holding an offending set because of multiple matches. I don't think Apple are going to be concerned with a single hit. Here in the news offenders are reported as holding many thousands of images.

[trynumber9]

Does it scan files within archives?

If it does, you could download the wrong zip and instantaneously be over their threshold.

[altitudinous]

The scanning is to take place within iCloud Photos, which handles images / videos etc on an individual basis. It would be a pretty easy thing to do for Apple to calculate hashes on these. I'm not sure how iOS handles archives, but it doesn't matter - remember it isn't 100% or 0% with these things - say only 50% of those people store images in iCloud Photo, catching out only 50% of those folk is still a good result.

[trynumber9]

Yeah, I'm not sure. Just is a bit worrying to me. On my device iCloud Drive synchronizes anything in my downloads folder. If images contained within zips are treated as individual images, then I'm always just one wrong click from triggering their threshold.