Because the department store isn't selling a design the buyer created. The design creator knows the design inside and out. They know, in their minds eye, what they expect the finished product to be before it's even printed and expect the printed finished product to look EXACTLY like what the envisioned in their minds eye..
An off-the rack crap print makes no illusions as to what it is. A mass produced, printed in Mexico or China semi-knock off of a truly great design, that is priced to fit on a store credit card.
It sits on the shelf for the world to see, touch and try on in the bright lights of a store. It is content to sit there unitl it sells or is clearanced out to still make a dime proft and the store is okay with that.