It’s a pretty weak argument to say that a clearly communicated change in behavior of a single application compromises trust in the entire operating system. You’d basically need to argue that Apple should not be allowed to install any default applications or services.
The Photos application can’t be removed, but this behavior can be turned off.
I'm no apple apologist but apple must follow the laws of the countries they operate in. They can't advocate for us because we are not the ones setting the rules.
The way to opt out of CSAM scanning on an iPhone is identical to opting out of it on Android: disable the platform's cloud service to synchronise your photo galleries.