They did come up with a more space efficient jug in 2008 and it was supposedly adopted by both Costco and Walmart. The same size shipping container would store 50% more milk. There is even a NYT article about it - http://www.nytimes.com/2008/06/30/business/30milk.html - but I only ever encountered milk in a container about half way between traditional and that design for one week a few years ago in my local Californian Costco.