It is outrageous, but it's not new. About 2 years ago I sold an item through the marketplace, shipped through Amazon, and at +30 days the buyer requested to return (my return policy stated no returns after 30 days). I ignored him, and then he filed a "Did not receive item" complaint with Amazon. They refunded him $250 and billed me $250. I fought it, using email, multiple phone calls (a trial in and of itself), showing them their own records of shipment, etc, the fact that the buyer had initially tried to return the item (and had sent messages to me saying he wanted to return it - implying that he had it).
I haven't used Amazon to buy or sell anything since. And you know what? It's great! I use Discogs (and my local music store!) for music, Alibris (alas, no good local book stores remain) for books, Newegg for electronics. I haven't yet found a great source for ordinary household goods online, but the local Home Depot/Costco/Target have me covered. When they get drone delivery and a good online experience, I'll be stoked.
In truth, I don't think Amazon can really compete within these niches. They get away with it because of an incredible focus on reducing transaction friction, and because they are usually "good enough" in so many categories. My worry is that Amazon will expand their monopoly, and then really start abusing it's customers, and they won't have anywhere to go.
I guess I'm just saying don't wait for them to try and screw you out of $250, give up Amazon for a month, and see how it goes! I think you'll be surprised.