I encountered plenty of vending machines where the stock is completely out of sight, and your only choice is buttons. The friendlier of these would display "out

I encountered plenty of vending machines where the stock is completely out of sight, and your only choice is buttons. The friendlier of these would display "out of stock" when you press a button and the item is out of stock, the less friendly would just make your coffee without sugar if it's out of sugar, or even sugary creamer water if it's out of coffee.