I agree, and I always wonder why stores don't cator to folks wanting to sell their firearms to them. But frankly, they really don't cator to these people at all and often offer 50% of value (often begrudgingly it seems). I can understand that on guns that don't sell, but I can't understand that on guns that move off the shelves.
I go into large gun shops with hundreds of new guns but maybe only 20 used guns on the shelf. I look at the price of the used guns and they approach new gun prices if they are in good shape.
My take on that is that they simply don't pay folks a reasonable price on a used gun. The price offered is almost insulting. Like cars, most people take the path of least resistance and with cars that usually means you trade as well as buy. I told one gun shop I would rather landfill the gun then sell it to them for the price they offered.
I do understand profit. But I also understand sales is all about volume for most stores.