As far as I understand it, all apps are given the Sensor permission by default in AOSP and most AOSP based systems, but it is a permission as any other and therefore has to be declared by apps.
What I do is have it disabled (for user apps) by default. If an app tries to access Sensors, I get a notification. This wouldn't probably happen if apps could just simply seize it...
But I'm sure some devs here can give a definite answer for this...