Using iphones, you have to trust apple, because everything is closed source and no one can audit the code to make sure that apple isn’t being nefarious.
Using AOSP (the open source android project) like CalyxOS or GrapheneOS, you don’t have to trust–you know. All the code is open source and is continuously audited.
The same can be said about Mac’s and Windows (both closed source) compared to Linux (open source).
Privacy is more than just a choice, it’s a conscious effort.