When telcos or the internet or core banking systems fail it shows that cash is king
Our leading telco Telstra had a full mobile wireless phone and data system failure recently.
Attributed to a very old network time server that had not been replaced and reset itself back to thinking it was 2006.
Soooo many people had meltdowns over only being able to use cash for payments. It was so funny to watch how different people coped (or didn't).