Stories from customers in Australia that cash wasn't a substitute, because it was the cash registers that weren't responding.
Now, pricing in Australia puts the total amount up front. Your burger is $4.50, the fries are $2.50, and the coke is $2. Your bill is $9. There's no "plus tax" bullshit to take the bill to $9.87.
So even if I had exactly $9 in notes and coin, I couldn't buy some food.
We had a major outage from one of the big providers in Australia recently (Optus). It was big - phone, internet and especially EFTPOS was down. And still the cashless proponents push their bullshit.
If I was the manager of an affected Maccas, I'd be telling people "Hey, our payment systems are down, but we'd still like you to enjoy our food, so you can pay us what you've got in cash, or nothing, it's up to you. We can't make make change so please don't hand us a $50 bill, but if you've got five or ten dollars in your wallet, that'd be great"