One of the reasons for that Menthol may be that there are various rules on what can be sold at the Fethiye 2nd hand market - nothing new, no electrical goods & no fake copy DVDs or CDs - these are quite rigidly enforced by the Zabita, who patrol at fairly regular intervals.
The space on the stalls is quite small & you're also not allowed to have items in the aisles in front of them. If you're unlucky & get a stall against the walls the space behind is so minimal, you couldn't get anything on the floor behind either.