Why should consumers be out of pocket for an item that has been returned and can be resold? If I pay £15.99 for something that has to be returned, I expect a full refund.
However, a good business will send a postage paid returns label.
If I buy something from a town centre shop & need to return it, the retailer will not refund my fuel & carpark fee, even if the item is faulty. It's reasonable for a business to want to verify a fault before refunding postage.
I sold a satnav on eBay, the buyer claimed it was faulty. He returned it to me & I found it was set to Polish and had Polish destinations set. Clearly it wasn't faulty. I refunded the purchase price for goodwill but refused to refund postage, as Fran says I'd already paid to send it out. He made an almighty fuss: eBay backed me.