I appreciate this well thought out and logical approach.

The issue I have is with the way this is presented.

I actually really like the local-only features related to making underage users second-guess sending/viewing potentially harmful content. IMO this is a huge problem especially since most do not have the context to understand how things live forever on the internet, and is likely a source of a large percentage of this "Known CSAM material" in circulation. I think it's a great step in the right direction.

But the scan-and-report content on your device approach is where it becomes problematic.
It's sold as protecting privacy because of a magic box "the cryptographic technology" somehow prevents abuse or use outside the scope it is intended for. But just like this entire function can be added with an update, it can also be modified with an update. Apple pretends the true reality of this feature is somehow solved by technology, glosses over the technical details with catchphrases that 99.9% of people that read it won't understand. "It's 100% safe and effective and CANNOT IN ANY WAY BE ABUSED because, cryptographic technology." They're forcing their users to swallow a sugar-coated pill with very deep ramifications that only a very small percentage will fully comprehend.

I'm 100% for doing anything reasonably possible in the advancement of this cause. But you're correct in that this is "one fear is more important than another fear." And I don't think anyone can say how slippery this slope is or where it can go. I also don't really feel like you can even quantify in a way that they can be compared the harm caused by CSAM or mass surveillance. So a judgement call on "which is worse" really isn't possible because the possibilities for new and continued atrocities in both cases are infinite.

But at least in the US, a line is crossed when something inside your private life is subject to review and search by anyone else even when you have not committed a crime. If you want to search my house, you must, at least on paper, establish probable cause before a judge will grant you a search warrant.

"It's okay, these specially trained agents are only here to look for just drugs. They've promised they won't look at anything else and aren't allowed to arrest you unless they find a large quantity of drugs" -- Would you be okay with these agents searching every house in the nation in the name of preventing drug abuse(which also is extremely harmful to many people including children even when they are not direct users)?

The argument "well just don't use apple" doesn't stand either. A landlord can't just deputize someone to rummage through my house looking for known illegal things to report. Even though it's technically not "my house" and you could argue that if I don't like it, well I should just move somewhere else. But I don't think that can be argued as reasonable. Our phones are quickly becoming like our houses in that many people have large portions of their private lives inside them.

I can't quite put my finger on the exact argument so I apologize for not being able to articulate this more clearly, but there is something with removing the rights of large groups of people to protect a much smaller subset of those people, from an act perpetrated by bad actors. You are somehow allowing bad actors to inflict further damage, in excess of the direct results of their actions, on huge populations of people here. I know there is a more eloquent way to descibe this concept, but doing so just doesn't seem like the right course of action.

And I'm sorry but I am not smarter than all of the people that worked on this, so I don't have a better solution that would accomplish the same goal, but I know that this solution has a huge potential to enable massive amounts of abuse by nations who do not respect what much of the world considers basic human rights.