WHY in Business and Hobbies can we only sell items placed on special shelving??

I can’t see the difference between selling small sculptures for shelves and large floor-standing ones, because both have exactly the same gameplay flow. But we’re able to sell the first, while the second we can’t. That doesn’t seem right.
And I don’t want to use mods — I paid $40 for a DLC, not to craft the game myself. It’s a matter of principle.