That's because they fuck over their sellers.
I tried to sell a modem which I had previously purchased through Amazon. The modem came both as a bundle and by itself. I listed it correctly as purchasing the modem only, listed it "like new" (when really it was basically new, not removed from the box). It was actually the lowest price you could get it used.
Someone bought it, shipped it to them faster than necessary. About a week later I got a notice from him saying that he wanted a refund because he had thought that he was getting the bundle (not just the modem as it was listed). Why they thought they were getting the bundle like new for that price is beyond me, but whatever. I rejected the refund because it was their mistake and it would have been too much work to be worth it. Sensible, yeah?
They initiated a claim against my account and Amazon withdrew the money (it was actually great timing - overdraft). The claim said the the item condition was wrong (it was not). You are able to contest any claim like that so I took the time to explain what had happened and why the issue wasn't even about the item's condition. I don't know if they just didn't bother reading it or if all responses are handled with robots because I get a very superficial answer that didn't even acknowledge what had happened. I repeated the process in order to try to talk to another person, wrote up another account of what happened (including the new non response), and got the same kind of non-response (you must list items under the correct condition, blah, blah, blah) from a different rep. Basically, they just didn't bother answering me. I'd already wasted way more time than necessary on what I thought was gonna be a little extra cash, so now some dude in Minnesota got my modem for free, and I got an overdraft for my trouble. That's a cool trick.
Got no clue what's going on over there but I'll never sell anything there again if I can avoid it. Worst customer experience ever.