Better than the refridgerator is the vending machine example. A man owns 50 vending machines, and has a route where he goes machine to machine restocking as needed. But he doesn't know except from experience, which machines more urgently need filling, and he doesn't know which items are out of stock. Those vending machines could easily send information to a central server(in his stock room) and an app on the server create a pick list for replacements and even a route to make the best use of his time.