I use cash mainly for convenience at yard sales and crowded bars/events in Finland. There's not many situations you'd need cash if you live in a big city, even yard sale transactions can be made with mobilepay.
Yep, there are still places in Finland where even young(ish?) adults find cash occasionally useful, especially in unusual transactions where the seller is not professional.
For example, if you start having kids, and going into their sporting events or whatever, you'll find that any form of electronic payment is most likely not accepted in the pop-up cafeterias ran by parents. No cash? No coffee for you.
Cash is still a handy way to give your kid some money to spend. I know some people already get their second graders a debit card with a monthly allowance, though.
But yes, about 99.5% of the transaction volume in my household is electronic.
In Denmark, in a noisy, busy bar, a card payment (especially contactless) is easier -- I don't need to hear the amount from the barman (obviously a challenge in Danish even in ideal circumstances...) and the barman doesn't need to return to me with the change.
The primary use of cash is shopping in Christiania.
