Economies of scale are huge here. You can store well below -40 when you're talking food for 100 million people, that just doesn’t work well when you’re talking one person.

Of note I didn’t say a year or 2’s notice 10 years of food on hand would be fairly cheap and we currently have the surplus to hit that number quickly. And that’s for 100% replacement, most situations aren’t going to drop food production to zero giving us more time.