I had a thought - I know for UPS you can refuse delivery on packages. Can you do the same for USPS?
If so, for large purchases, it might be a good idea to weigh the package before even opening it, to confirm that the weight is at least in the ballpark. If the weight is drastically lower, you could then refuse delivery and avoid scammers who try to send you an empty package to spoof the tracking.
Would that work? What do you think? If you did the transaction through Paypal, would they consider it an undelivered package and allow you to be refunded?