There is a little LED that lights up when they open. The door latch is controlled via software and so is the light, though I would assume in the case of power failure they'd unlock for fire safety reasons.
I know where you were going with that, but the situation is different than what you’re trying to show. On Macs the light is on the path of the camera: if it is on the camera is, if it is not then the camera is not. Whereas with the door you might think that if it was latchless someone could just push it open when the light was off. The camera light is really a door alarm, not a door latch. (And as I just mentioned, doors with an alarm but no lock often do exist, usually for fire safety reasons).
A door without a latch does not prevent
an unauthorized person from trespassing.
A camera without a cover does not prevent
an unauthorized person from trespassing.
