[vetinari]

Since Android v1, it offers APIs (intents) for picking items belonging to other apps or doing an action on behalf of other apps.

Applications do not need access to gallery; they can ask the gallery to let the user pick the pictures he wants to work with; the app does not need the access to camera, it can ask the default camera app to let the user make the photo and get the result. The app does not need access to telephony; it can ask dialer to dial a number on it's behalf. Etc, etc.

The developers didn't use these APIs because users were asking for iOS style integrations, where any apps does everything for itself, instead of using system components. So they got it.