I think, in this case, it's more to do with buying time. It can take well over a month for even legitimate items to arrive from China, and a valid tracking number makes the guy seem plausible. People won't know for sure they've been scammed until they actually receive the item. So the guy has at least a month to collect as much money as possible, clear out his Paypal account, and disappear, before Ebay cartches up with him.
It's the same with the nonsensical cut'n'paste replies he gives to messages. He knows that as long as he replies within a certain timeframe, he can stay under Ebay's radar. This is where Ebay pays a heavy price for having a system that is largely automated. It's easy for scammers to game such a system.