Two different situations - cash from cash businesses vs. emergency cash. Reading between the lines, I think the OP was talking about emergency cash. As others have noted, in a true national emergency cash may have value for only a couple/few days given what's happened in other countries over the past hundred years. Also as others have noted, that cash depreciates over time, and would even faster in a grave national emergency.
True, but the same thing would be true for money in a bank or even a brokerage account. In a doomsday scenario, it’s all going to heck. The only thing left then is what you can physicall protect from roving gangs.
I learned back in my trucking days that there is a difference between cash and other forms of payment in many scenarios.
Having enough Benjamins to pay for a problem will get many a mechanic to come out and roll around in the wet snow at 11 pm. Probably because he can hide it from the wife, ex or the government. I don’t care, I will never be without enough cash to pay for a trip across the country, a substantial car repair or medical expense.