Glock doesn't count that as a safety but there is a third safety. There's the "firing pin safety", the "trigger safety" and a third internal safety that Glock calls the "drop safety". A "ramp" in the trigger housing locks the trigger bar in the up position effectively turning it into a redundant firing pin safety until the trigger is pulled sufficiently to the rear to disengage the trigger bar from the ramp. The firing pin safety blocks the firing pin's forward motion, the drop safety holds the firing pin immobile from the rear and the trigger safety prevents the trigger bar from moving unless the trigger is pressed. If you want to count the fact that there's not enough stored energy to fire the gun until the trigger is pressed, that would be four safeties. But I agree with you, that's not a safety, it's just how the gun works.