In my articles on emergency preparation, I've frequently mentioned the need to have an emergency reserve supply of cash on hand, in relatively small bills, so that if the power goes out, you can still buy what you need. I've referenced a number of real-world examples where this has been a problem.
Now Sweden's government makes it official.
Everyone in Sweden has been urged to stockpile coins and banknotes in case the country’s move towards a cashless society leaves them without money in a cyber-crisis. In a move that will sound alarm bells in the UK, Sweden — one of the most advanced nations for digital payments — has warned that its people could be unable to buy anything if its computer networks were put out of action.
The Swedish Civil Contingencies Agency, an arm of the government, has sent guidance to every home telling residents to squirrel away “cash in small denominations” in case of emergencies ranging from power cuts or technology glitches to terrorism, cyber-attacks by a rogue government or war.
There's more at the link, although it's unfortunately behind a paywall.
This is significant, because Sweden's about the most cashless society on earth! Its companies and stores have for years tried to encourage all transactions to be paid via credit or debit card, or other electronic means, so much so that Sweden's central bank has had to intervene to ensure that those few citizens left out of the electronic loop can still find (much less use) cash to meet their needs.
There's also the aspect of privacy, of course. Paying in cash for something, particularly between private seller and private buyer, means that sales tax and other costs are usually not paid. What's more, there's no official record of the transaction. I find that particularly handy when buying something that someone might try to confiscate, regulate or register one day. If they don't know I've got it, they won't bother me about it.
I also recommend keeping a store of value in non-cash items, such as silver and gold, readily tradable commodities, etc. If things go badly wrong, you can't eat cash, but you can eat a can of food, or drink a bottle of something, or smoke a packet of cigarettes. Swapping any of the latter for fuel or other essential supplies may be the only practicable transaction under some circumstances. Barring that, however, cash is still king, even though its demesne is diminished these days.