At least on iOS, things like microphone permissions are opt-in rather than opt-out. iOS also displays an icon prominently at the top of the screen whenever an a

At least on iOS, things like microphone permissions are opt-in rather than opt-out. iOS also displays an icon prominently at the top of the screen whenever an app is using that permission, and regularly reminds users when they leave an app running with these permissions in the background, so it's kind of hard to miss when it is happening.