A) Right. We have universal single payer food insurance, also known as taxpayer funded welfare for the poor. We're in essence covered by, and paying premiums to, a mandatory State-run insurance policy such that if we ever can't afford the minimum necessary food to survive the State will (at least in theory) step in and buy it for us from the open market.

B) Let me rephrase. I'm not going to wake up one day to find that my required daily calorie intake has increased by multiple orders of magnitude. There are very few household budgets that could reasonably be expected to absorb such a shock, no matter how efficiently the market for those calories functions.