In January Barlays digital went down for three days. Today it is Lloyds, Halifax, Nationwide, TSB, Bank of Scotland and First Direct. These things always seem to happen on pay days.
People cannot get money out, transfer funds or pay for goods and services. It might no be so bad in a shop or supermarket where you can put the goods back, but what if you topped up in a garage. You cannot take the fuel back out. Then there are DDs which come out automatically, but if your pay has not gone in you could be driven into an unauthorised overdraft.
I have only ever been caught out once and that was enough. I now carry an amount of cash, but not in my wallet. It is folded behind my bus pass and that is in its own window wallet. And all my (few) DDs are scheduled for mid-month so that funds are always there.