I think the point is more that it's strange that these giant retailers who've gotten to where they are because they are basically experts at selling goods retail are creating these arbitrage opportunities and largely ignoring them. Intuitively, what you'd expect is for the retailers to find a way to close the arbitrage gap. But in the U.S. we have this kind of strange notion of retailers setting prices based on guidance from the wholesaler or producer and then not allowing any price negotiation. These retailers are used to a world in which realizing the resulting arbitrage was not worth anyone's time or money but the internet has changed that and they haven't adapted.