> 2 day shipping is cost effective to amazon when most goods are near the customer. This is true. However, Amazon wants "2 day shipping" to be 2 day shipping,

> 2 day shipping is cost effective to amazon when most goods are near the customer. This is true. However, Amazon wants "2 day shipping" to be 2 day shipping, not probably 2 day shipping, which means they need to deal with the long tail of orders. And for that, you need airplanes.