Amazon is the one that advertizes the price. Once it's advertised and a transaction has been completed, that's a contract. That contract includes the possibility of returns because they compete in the retail space, where there is an asymmetry in that the company has had ample opportunity to evaluate the product and price it accordingly, but the customer doesn't otherwise have much to evaluate on. If Amazon does this at such an astronomical scale that they don't notice a big price discrepancy, that's the cost of operating such an astronomical scale. They still made the contract - and it was even their lawyers who wrote the contract and spend hours poring over it. If I order truck loads of landscaping material to be delivered to my house and I later learn that it wasn't such a great price, you better believe I'm now stuck with that material and the bill.
I actually had a similar event happen in a real-world retail store. They were advertising frozen chickens for an absurdly low price. I checked with an employee that the price listed was not a mistake - they said it was correct. I grabbed a manager, and checked that the price listed was not a mistake - they said it was correct. I took 2 cart loads of frozen chickens to the front of the store - and they didn't notice the price was absurdly low until I had already swiped my credit card and the cashier was telling me the total. By the time she grabbed a manager, the transaction was complete, and the same manager who confirmed the price now told me it was a mistake. Fuck them - they listed the price, I checked, I finalized the transaction.