Like I said in my unpopular comment, I dont buy it. I dont buy that canning, freezing, and drying food cant lead to a long term storage reserve. Is it a geographic size issue, that the warehouse space cant possibly exist?
Lett's say famine hits for one or two years, and we actually do get better about wasting food. Two years of famine year food usage is 1.33 years of current food usage. Its not possible to reserve that much food for the current population of a country, even dried? It sounds more like we just dont want to, the benefit doesnt outweigh the effort, or nobody wants to pay for it.
Your solutions can exist. Whether they should or not is an economic tradeoff problem. Production is not free, storage is not free either. Neither one of us have been arguing with hard data yet regarding total $ costs, or evaluation of long-term risks, but the tradeoffs do exist.
The U.S. grows 13 billion bushels of corn per year (https://en.wikipedia.org/wiki/Corn_production_in_the_United_...). Of this, it looks like about 1 billion bushels go to feeding U.S. residents directly. I tried to lookup the volume of corn silos in the U.S. to get a good figure for how many years' worth of consumption we keep lying around, I haven't found anything yet.
And this is all looking at a pretty low-level survival grain- canned foods are a bit more expensive to store, then fresh produce, then frozen foods, then fresh meat, etc. (approximately). These foods are also more expensive to produce.
Id be curious to see an estimate of cost to store 1 year of sunflower, pepita, dried salmon, dried seaweed, dried spinach, dried blueberry. I am imaging a really gross salmon trail mix can, you eat one can a day.
What is the main enemy of storing what is basically mass birdseed? Light/heat spoiling the fats?