As a seller there is more than 1 way to prove you sent a item that you have sold. But hey if that for whatever reason that tracking number isn't working you will have eBay stealing money out of your account to refund a buyer. So you have given away your item and paid eBay to sell it and paid the freight. Just because freight maybe a little slow during these times something a seller has no control over. Even when things do go ok their seller fees are a total rip. As a seller my advise is to keep away from eBay.