The reason I'm buying an iPhone is I don't have the time to care about how high the walls should be and to ensure every app I use isn't abusing the SDK to suck up data. The reason I'm paying a premium for Apple is I'm choosing to trust them rather than trust every developer.
Unless you don't install any app, you still trust all the developers of the apps you install. Walled garden is just a nice way to name Authoritarianism applied to a platform.
It might make you feel safe to have apple deciding every bits of what you can do with your phone but it does mean that: - it's secure - the apps you are using are - you still have very low control over your data.
You just pay to close your eyes and feel safe.
I’d rather trust Apple than the cumulative two dozen developers that have their software running on my phone.
Where is the evidence that any of that was required?