So theoretically your saying its not costing the seller anything apart from a few seconds of their time.  Have to disagree with you there.  Its cost money and time in the first place to buy the product before you even get to taking photos, editing and finally listing it. When you go to an Auction House to bid on items they have your Bank details, ProoF of Identity 100 point check.

Yes, but when you paid for the item you were buying it with the intent of selling it, it wasn't bought specifically for one buyer who didn't pay. If the buyer doesn't pay you can just relist the item; you haven't lost any money, you still have the item.

Once again, ebay is not an auction house, more like a tender centre