Imagine I ordered a product online, and it gets shipped from China to Europe. One day, the tracking service offered by the chinese postal company claims that the package was successfully delivered and given to the recipient, when in fact, no such thing has occurred.
Upon contacting the seller, the seller claimed that the product was delivered by the chinese postal service, using their tracking service as evidence.
In such a hypothetical scenario, what would my options be? I'd have no way to prove a negative, or that I did not receive the package. Indeed, the seller could believe that I was lying and wanted a refund while keeping my package.