I know several of my guns came with test targets so they were factory fired. I certainly do not considered them used. I also have guns that I have bought but never fired that I also consider new. While I enjoy reading about the car analogy, once a car is titled, it is considered preowned if it were to be sold. If a gun is purchased and never fired by the owner, I would say it is still new. It may be semantics, but we can just call it owned but never-fired for better clarity.
The ATF should be a convenience store instead of a government agency!