Here's why...Unless it was a used gun why would you expect just because it was in a rack to get a "discount"?
Because one has no way of knowing how previous customers have treated the display model when they handled it.
Rimfire - get me one from the back. I don't know how many times some rube has dry fired the thing.
Most rifles - don't care unless - see above
Most revolvers - don't care unless - see above
Semi-Auto pistol - get me one from the back - especially if it's a 1911 platform. I don't know how many times some rube has let the slide slam forward on an empty chamber (bad for 1911's not sure about other platforms).