That may be how it works in practice DTC but it is hardly ideal if only a precise set of actions results in you not being shot. Imagine if it were a newcomer to the US who never knew the "rule" you describe, but naturally thought that, hey, the police have stopped me, they'll probably want to see my ID that's in the glove compartment so I'll just get tha -- and then bang, they are dead, which is OK becuaase he "might" have been reaching for a gun.
Possibly even, that is what some people are doing. It's a sad state of affairs, though, when the police can claim that this was likely enough to justify firing.