The article says that Apple calls this system neuralMatch. I'm not sure why that name gives you confidence that there is zero AI involved?
They did add a classifier to iMessage. But it's designed to prevent children seeing any sexually explicit images.[2] There wouldn't be a reason to train it on images of children specifically.
[1] https://www.apple.com/child-safety/pdf/CSAM_Detection_Techni...
[2] https://www.eff.org/deeplinks/2021/08/apples-plan-think-diff...
Perceptual matching is used to sort categories of images. A quick DuckDuckGo will turn up many results. No stretch of the imagination will turn this into a bit for a bit comparison. This is a machine learning algorithm used to categorize images. https://www.ibm.com/blogs/research/2019/10/learning-implicit...
Matthew Green is tweeting about this: https://twitter.com/matthew_d_green/status/14230711866160005... and mentions that it is "preceptial hashing”
9 to 5 Mac article, in which they restate that it is not a classical bit-by-bit hash:
https://9to5mac.com/2021/08/05/scanning-for-child-abuse-imag...
“Perceptual hashing is the use of an algorithm that produces a snippet or fingerprint of various forms of multimedia.[1][2] A perceptual hash is a type of locality-sensitive hash, which is analogous if features of the multimedia are similar.”
https://en.wikipedia.org/wiki/Perceptual_hashing
The goal is to verify a black and white copy of an image is identical to a colored original. Search algorithms want a similar thing so they can validate an image contains a blue car. However, a perceptual hashing algorithm must differentiate between different images containing a blue car while matching a photoshopped copy of the same image.