Appears to me that Koreans are fighting a lot in Retail space. Earlier, Tesco (Home+ in Korea) launched Virtual Grocery store which is a big hit. Now its competitor came up with this innovative idea. More innovations in pipeline ;)
Fast, asynchronous delivery is part of the puzzle. Waiting around for amazon deliveries is a pain; but for low-value groceries, the risk of theft isn't as serious. It works OK for newspaper deliveries, and when I was a kid we had milk deliveries left outside the door with no problems (yes, horse-drawn).