[DoctorOW]

Hashes don't really work that way. They don't actually give any high level of a photo's contents. You can't ask a hash to find all photos of a certain document or a meeting or anything like that. They really only detect exact copies, which makes them somewhat useful only for the most basic of copyright infringement (i.e. proving someone has a copy)

[4bpp]

As far as I remember, Apple's proposal was to involve https://en.m.wikipedia.org/wiki/Perceptual_hashing which is meant to sidestep this exact problem - and either way, your objection would be equally applicable to CSAM. There is no mechanism that works better for it than for copyright enforcement.