The buyer can make a fraudulent claim and get his money back. There is no way to prove he got the money if he claims he doesn't own the wallet, and there's no

The buyer can make a fraudulent claim and get his money back. There is no way to prove he got the money if he claims he doesn't own the wallet, and there's no way to prove he owns the wallet unless he ties that wallet to himself somehow. (which is possible but not reliable, and countermeasures exist anyway)