As proved by various outages, when electricity (or the internet, or the service provider, etc) is down and prevents digital transfers being made… cash doesnt work either, cause it’s all the same POS / accounting software that handles cash which is also down.

Also if a natural disaster takes out internet access for an extended period, wheres the cash a business needs to keep on hand going to suddenly appear from? I haven’t worked in retail in a decade or more, but we always kept as little cash as possible on hand due to the constant threat of robbery. Even back then cash was way less than 50% of transactions, I’d be surprised if it was even in the double digit percentages anymore.