In a roundabout way with my insurance background I can confirm some of what that trucking article is saying. Most school cafeterias, nursing homes, restaurants, fast food/convenience stores, and probably most supermarkets only have refrigerated space to store a limited amount of fresh, perishable and frozen foods, probably only 72 hours worth max and that is on a standard 3 "busy" days, not all out panic buying.
Its not only hard for most of those places to have massive refrigeration units due to space and money constraints , but having massive food storage on site can lead to mixups, spoilage, run ins with heath inspectors, and accidently selling past due food and getting someone sick. Its just easier and more economical for them to rely on regular deliveries. Look at most supermarkets building on the outside, then look at the retail space on the inside. There isn't that much difference, and that is not including break rooms, bathrooms, offices, employee lockers. Most supermarket stockrooms I have been in have been nothing more than hallways with single pallets on one side and pallet jacks. Only large mega stores might have floor to ceiling heavy duty shelves and forklifts. Even with things like canned goods and non perishable stuff, its usually what is on the shelves, some extras in overstock ( the boxesy the try to keep out of reach above the store shelves, but if your tall and crazy like me you end up helping yourself), and maybe if they are lucky enough in the back stockrooms to refill the shelves just one more time.
Throw in a disaster and panic buying and most stores selling food and essential goods will not be able to keep up. I seen this happen in real life with not one food stuff and batteries with a threat of a storm, but I seen it happen regionally after Hurricane Sandy with even non food stuff. Think about those plastic and metal gasoline cans they sell in Home Depot, Walmart, Gas Stations, etc. Right now if you needed one you could probably think of a dozen places locally where you could buy one, right. 3 days after Hurricane Sandy hit, every store in my area was out of Gas cans, and most walmarts, and sporting good stores were out of everything from Mountain House meal, to sleeping bags and propane fuel bottles for camp stoves....oh by the way, I had zero damage in my town. I am 100 miles way from NYC and North NJ were Sandy impacted. People from that area were driving long distance into PA, DE, MD, and CT and clearing out our shelves because their shelve were bare.