Amazon doesn't sell every product themselves. Most are Amazon Marketplace sales, which are entirely 3rd party (some are Fulfilled by Amazon, which gives you the Prime shipping but is still 3rd party). In these cases, Amazon can't control the prices at all; it's all up to the 3rd parties to set the prices.
Disagree. I've never seen Amazon itself sell LEGO above retail price. They just tend to run out of stock, so they don't actually sell many sets. Third party sellers often do up charge, but that's basicaly like buying on eBay.
OTOH Toys R Us will definitely sell above retail. Set 60057 is $17 at Amazon, $20 from Lego, and $25 at TRU.
LEGO pricing in general has been inflated recently. Flippers and 3rd-party Amazon sellers know this, so they buy up all the stock to resell via Amazon FBA. It's a LEGO bubble right now with a lot of artificial demand. Some of these flippers will coordinate massive regional buyouts of a given LEGO set from retail stores by using people from Fiverr, etc. and then hoard the bulk lots or sell to collectors.
