I can only assume that up until P developers could record both sound and video in the background. That's some scary shit.
[edit] Why isn't there a system level visual indication or audit trail of any camera or mic access? Surely this would be trivial to implement, you could even disable it if you just didn't give a toot about privacy at all.
Indeed. Finally in Mojave Apple is adding direct control over which apps have access to the camera and microphone, but in general iOS is miles ahead of macOS in regards of privacy control.