This is dangerously naive. The US justice system alone will hound people on goosed up charges and try to get people to accept a plea deal and write a bogus confession. Parallel construction. Additionally if you can't audit the database (I'd bet very few people can, including your senator) how do you know a hash of something not CP wasn't inserted into the database. This entire system screams ready for govt overreach. It's worse than normal since there'll be no public evidence when it's abused.
Documents could also be engineered to trigger false positives, making it difficult or impossible for a corporate whistleblower to photograph incriminating evidence to deliver to the authorities.
So, if the rumors are true and every iPhone will check every photo against an opaque database of perceptual fingerprints, what safeguards exist (beyond "trust us" from the database keepers) to prevent abuse of the feature to suppress evidence and control the flow of information, and which organizations or governments will have control over the contents of the database? As always, who watches the watchers?
I have to assume humans are involved at some point before journalists are notified. The false-positive will be cleared up and no reputations sullied (except perhaps the reputation of using AI to scan for digital fingerprints).