On startup installation, macOS and iOS do have opt-in screens for certain things like analytics, improving Siri, stuff like that.And yet there is some data stored in my iCloud account, even though the first thing I did when I bought an iPhone was spend an hour turning off every setting that I could see that would permit uploading anything. How did that happen? Apple introduced some new settings in a subsequent iOS update, and defaulted them to being turned on.
It's easy to find fault in retrospect but it doesn't make sense to have opt-in screen for every conceivable feature.
OK. Just provide a single, clearly marked option to enable or disable telemetry globally, and require that all Apple software and all apps in the App Store use APIs that are gated by that option for all relevant data uploads. That would be very clear about user intent, if you want to be seen to support user privacy as a genuine goal.
Apple generally has a great track record of responding to criticisms like this and making things clearer for users.
And yet huge amounts of data uploaded to iCloud still isn't end-to-end encrypted, even optionally. A lot of Apple users don't realise this, but plenty who do have called Apple out on it for a long time, and it hasn't been fixed. You can read whatever conspiracy theories and subjective arguments you like about why that might be, but the insecurity is an objective weakness in the system that hasn't been fixed.