In the private sector, it’s not uncommon for the party that controls a distribution channel to extract rent from both ends.

For example: I know a guy who worked for a startup that made a new kind of low-fat mayonnaise. They had trouble getting their mayo into grocery stores, because the grocery chains charge fees (something in the five figures, IIRC) for giving new products shelf space, and the company didn’t have enough cash on hand to pay those fees.

η http://en.wikipedia.org/wiki/Slotting_fee