It's getting easier to live life without cash in your wallet — or without a wallet at all. We can go shopping just about anywhere with just a credit card or smartphone. I buy most things on card... but I also make sure I keep a small amount of cash on me just in case.
I know a handful of people who refuse to carry cash now. They buy on card, or don't buy at all. That puts them at the mercy of failures and mistakes. Electronic payment systems sometimes fail. I was once mistakenly locked out of my bank account for days. Why not carry a little cash to mitigate these rare but predictable situations? I think you're foolish if you refuse to carry cash.