The return system uses weight. There is a scam ppl have done where you order something then switch it with the same weight in rocks or sand. Then send as a return to get your money back. So I assume a empty box wouldn't have the needed weight and would be flagged.
I dont know if this is what you mean, but I once recieved an empty package and it was a struggle to get a replacement. It doesnt fit any categories they recognize. It's not 'did not recieve' ( there was even a delivery pic), there's nothing to return. I had to chat (IM) with someone multiple times.
The package gets weighed before sending and after receiving. There were a lot of articles years ago speaking of people who put stones in the package and sent it back, received the money and someone else got a package with rocks