[gumby]

Distributors for the big food companies (Coca-Cola, Pepsi/Frito-Lay, etc) essentially rent and maintain a section of shelving and then keep it full and decide themselves on the distribution of products that appear. Smaller manufacturers sell their product wholesale to the stores who then stock them in the normal fashion.

The end caps of isles are sold to the highest bidder, typically by the week; if that bidder is coca-cola they manage that display as well, subject to the constraints of the store.

One of the innovations of Frys Electronics was to try to run their shops that way, as they started by selling serial cables and other computer supplies in their family's grocery chain. It only partially worked as the vendors weren't really equipped to do this, the way the food companies are.