In addition there are contactless payments nearly everywhere -- it's becoming an oddity to have to insert your card for any payment under £30.
I definitely haven't used cash in the last two weeks, and I think maybe only a handful of times in the last few months.
That's not too much of an issue in Europe.
That being said, I've not given money to an homeless person in ages. Whenever asked I simply answer "I only carry cards, sorry" and they immediately lose all attention towards me.
In the UK I find that I need cash a couple of times a month, usually a market stall (most seem to use iZettle, but some don't). Occasionally you'll also get a cab trying to con you by saying their machine's broken - and suddenly getting it working again when you cite the law to them (they need a working card reader in London).
It's mostly debit cards, not credit. So the merchant fees are low.
Sweden also introduces new coins and bills a few years ago, and then a lot of people just gave up on cash.
There's also the 'Swish' system for sending money to people. You sign up and link your mobile number to your bank account. Then you can send money to a phone number, and it instantly goes to the linked bank account. Swish is popular for splitting bills, selling used items, market stalls, charities and such. Even some local stores take Swish payments, although that's not what the system is intended for.
The UK's PayM is similar to Swish, but the UX is not as good. Sweden is actually a bit behind the UK on contactless though.