There are way more egregious privacy concerns than sending non-reversibly encrypted noisy photos to Apple. Why draw the line here and not the far worse things happening on your phone and computer right now?
Almost every single app today interacts with the network in some way.
You would be constantly annoying the user with prompt after prompt if you wanted to get consent for sending any relatively harmless data off the device.
My Calculator app does not need to call home.
A good portion of the apps I use fall into this category, and a straightforward mechanism to opt them out of access would be welcome.
They have option to disble if they care.
"Computer, I command thee to send this and only this information over the channel of my choosing, using following encryption scheme, for here be my seal of approval for anyone who might want to verify, and here be the key"
"Sicut Vult"
On Apple's scale, most people care about the things they can do, not about how it happens. For that reason, default matters when the option is only about the internal process pipeline and privacy.
As a result, it is enough to showcase that in case some expert investigates the matter, they show that privacy is considered in a reasonable level.
Maybe some day in the future these things are common knowledge, but I fear that the knowledge gap just increases.