Referred to as a service by couriers such as UPS
etc. In fact it is simply another way of getting royally screwed.
A broker presents a package you are mailing internationally to the appropriate customs officer and says "Please slap your country's import duties on this item."
He then proceeds to add his own fee of approximately 150% of the customs and duties, and delivers it to the recipient who then has to pay the driver a sum of money which may be more than the item's net worth.