When I hear about this happening with small Etsy shop packages on Facebook everyone always tells the seller to have the buyer submit a police report. With that you (or the seller? I'm not sure which side handles it) can file a claim with USPS, at least according to what they say. The police report is less about expecting the police to actually help and more about proving you're not lying to try and get free or extra items since filing a false report is a crime.
I've never been in this situation from either side so I'm not entirely sure if it works quite this way but its worth a shot.
Shouldn't you still be able to file an item not received claim? Your ebay sellers should have insurance. (And yes, as BlueRose said, still file a report).
Edit to add: I had this happen last year, only I was the seller. My buyer received a package that should have had three MOC ponies in it, and it only had two. The parcel had been tampered with. I took pictures, filed a report with the post office, filed an insurance claim, and got money from the claim. So even though it shows as 'delivered', you can still file an insurance claim. (I am in Canada, and sent via Canada Post).
You could file a claim with USPS if you have a package that is obviously damaged/tampered with. The problem is that there is no package at all. In my personal experience, USPS will not let you file an insurance claim for an item that you say has not been delivered when tracking says otherwise (I can see why in some ways, since this would open up a huge gate for scamming). In their eyes, if it says delivered, it has been delivered. They generally won't accept responsibility for possible mistakes made. Maybe they would consider reimbursement if there was proof of a police report. eBay will discount "item not received" claims on the same grounds since tracking says delivered which is all the proof a seller has to provide (however, see my below comment).
When I hear about this happening with small Etsy shop packages on Facebook everyone always tells the seller to have the buyer submit a police report. With that you (or the seller? I'm not sure which side handles it) can file a claim with USPS, at least according to what they say. The police report is less about expecting the police to actually help and more about proving you're not lying to try and get free or extra items since filing a false report is a crime.
I've never been in this situation from either side so I'm not entirely sure if it works quite this way but its worth a shot.
^This is true. I had one instance where I purchased something from someone on eBay who was a scammer (a very clever one in some ways), packaged showed "delivered" in my zip code and ebay said they wouldn't do anything unless I filed a report with the police. I filed the report with the police (which I have to admit was so awkward). Then I had to go to some other building to get a copy of the report to send to eBay. Where I live they will not release police reports even if you are the one who filed but they did give me a document proving I had filed a report with the name of the officer, date, etc. This was enough for eBay to finally give me a refund. I will say it was a huge hassle though, it took a lot of time and frustration. I probably wouldn't have done it if it hadn't been such an expensive purchase.