I had assumed this was common knowledge that this occurred. We used to experience returns like this all of the time that Amazon would accept up-front before acceptance by our warehouse. >$200 chargers returned in original boxes containing $10 chargers. There have been other stories of iphone boxes full of playdough or just anything that would weight roughly the same.

I wouldn't be surprised if there are other 3rd party fulfillment providers that rather than dealing with having had this pushed on them by Amazon, they just put that return back on the shelf and they get shipped out to other customers.