I understand an app losing access to the camera in the background is a security feature. But, it is also really annoying when you want the person to see you while you’re doing something else on your screen.

One feature that’s been in the iPad for a few years and coming to the iPhone in the fall is picture in picture where a video call doesn’t take up the entire screen and as long as PIP is enabled, you can have your video call minimized and do something else.

Some other comments here seem to indicate (at least in recent models?) that it's a visual indicator light on the phone that the camera/mic is being accessed. That might be sufficient, although I might also like a small audio cue on lock (or camera engage/disengage while locked).

Unfortunately, I doubt Android will ever be able to rely on a separate visual indicator of recording, since that's another hardware component and probably hard (if not impossible) for Android to enforce.

Also not an iOS developer, but I think that apps enter a “suspended” stage when you close them or press the power button to save battery life. If you look at apps’ crash logs, you can see that they are occasionally killed by a system process for using too much CPU or other resources when they’re in the background.