I would like to believe though that for this system to fully fail an innocent person, the following would all need to have failed:
1) Coincidental CSAM hash collision 2) Incorrect manual review by Apple 3) Incorrect subsequent review by NCMEC 4) Inability of a lawyer to obtain the original image for presentation during a trial/appeal
which seems kind of unlikely? (although it's certainly the case that once steps 1, 2 and 3 have failed, the person's reputation is likely damaged even if they are able to prove their innocence in court).
The wider question here is, should 100% accuracy be the bar by which we judge this? I don't think we expect the law enforcement system to be 100% right, hence principles like the presumption of innocence and right to appeal, and even then it gets things wrong sometimes.