The customers draw products from the 'shelves' as needed and this can be detected by the supplier who then initiates a replenishment of that item.
It was the observation that this 'way of working' could be transferred from retail to manufacturing that is one of the cornerstones of the Toyota Production System (TPS).
However, the Toyota Delegation first got inspiration for their production system at an American Supermarket (a Piggly Wiggly, to be precise).
The aim of the 'market' is to send single unit consumption signals back up the supply chain so that a demand leveling effect occurs.
Toyota use this technique and demand it of their suppliers in order to generate focus on the supply issues it uncovers.