That sounds like a bigger loss of money - having the postman collect a couple dollars for every package would be labor intensive and result in multiple delivery

That sounds like a bigger loss of money - having the postman collect a couple dollars for every package would be labor intensive and result in multiple delivery attempts, and if the recipient didn't pay, then they'd have to return the package to the shipper, so the package would have 2 trips through the system. Collecting more money from the sender sounds like the better solution.