This was a bit of a surprise for me when I moved to Ireland and later the UK two years ago. In Sweden I wouldn't use bills and coins sometimes for months. Suddenly I have had to get used to carrying these around again, and having to pay fees when you pay with cards etc. I'm looking forward for the world to go cashless, and think this will happen very fast.
What fees do you have to pay in the UK when using a card?
Where it makes more of a difference, though, is that the fee charged to the merchant is a sufficient disincentive that it's pretty common for small shops and bars to refuse card payments under £10. This is even true of the new(ish) contactless payments that only work up to £20 and which were touted as replacing cash.