I ordered something from ebay a couple weeks ago. Post Office tracking showed it was delivered but I never received (don't know if they left it in the wrong place or if it was stolen off my doorstep, which has never happened before and I've lived in the same place a long time).
I checked with the post office. They were unable to locate the package but said because the shipment was sent Priority Mail it included insurance but the shipper would have to file the claim. The shipper wouldn't do anything further and Ebay closed the case because tracking showed it was delivered.
This was only a small amount of money so not really a financial issue, but I'd think the seller would at least go through the motions of making the claim with the Post Office,