This seems like a trivial thing to abuse
(and I'm sure many do).
I can't speak for Amazon, but at my employer, when a customer phones up or e-mails the customer service rep immediately sees certain details - number of orders by address, lifetime spend, spend in last 6 months, age of account and address, percentage refunds, fraud flags and so on.
Needless to say, the more legitimate an account looks, the easier it is for them to get no-hassle refunds.
Heck, this happens at my company, and we're 2 co-founders and a CSR. This was literally one of the first things we built - as I imagine it must be for any biz that ships products to customers.
Thats true but I'm sure Amazon has some form of blacklist somewhere in their risk management process. Or maybe that is not tied to csr changes and only in order processing.
Having shipping patterns change especially to a ship forwarding sites is highly suspect. There are databases that can help flag these either done commercial or collected internally. I'm sure Amazon has a pretty extensive list.
Needless to say, the more legitimate an account looks, the easier it is for them to get no-hassle refunds.