Sweden heads the vanguard. On a sunny weekday in April, the fruit and flower stalls of Stockholm’s Hotorget market were doing brisk business. But even here among traders who have tended to fly below the radar of tax collectors, not much cash was changing hands. Instead, many of the bouquets were being bought via card machines or Swish, a popular app that allows you to make payments with a mobile phone number or QR code.

https://www.ft.com/content/9fc55dda-5316-11e8-b24e-cad6aa67e23e