In the old days, postal services used to charge the recipient of a letter to deliver the letter. Then stamps were invented, and postal services charged the sender of the letter, and the recipent got free delivery.
Now there is free-shipping, and pre-paid return envelopes for DVDs.Of course, the shipping isn't really "Free." Its built into the cost of goods sold.
There is no universal, fixed, unchangable way of allocating business costs.