From what I read, and from what I know personally, being able to take an arbitrary shopping cart of items, and select the most efficient box is a huge advantage

From what I read, and from what I know personally, being able to take an arbitrary shopping cart of items, and select the most efficient box is a huge advantage. You can absolutely improve your margins by trimming your shipping costs to a minimum. Although the article doesn't mention it, I suspect UPS is doing most of their carriage. Anyone know for sure ?