5D3 Brand New - Over 6000 Shutter Count

It's not possible to just use miles or actuations to depreciate a car or DSLR. You also have to factor in depreciation which comes from risk. If someone had used a camera for 30 days, even if it only had 2 actuations on it, I wouldn't want to pay full price. I have no idea how that camera was treated. Was it dropped ? Was it used in the rain ? Some damage may not show up until later. Using your car analogy, what if someone had taken the car home for 30 days. Even if it only had 30 miles what if that person decided to use it for some abusive "joy riding ?" Test driving a car at the dealer is very different than taking it home for 30 days with no supervision. I may not care if a DSLR box was opened and examined in the store but I wouldn't want one that was opened by someone at home and returned after 30 days, even if they both had zero actuations.