QR code menus are extremely popular in countries that have wide digital payment adoptions, such as China.
Each QR code is linked to a table number. You take out your phone, turn on the camera with one click, scan the code, select the items you want to order, then click “pay”. It will take you to your digital payment provider (in China it’s often WeChat), which already has your payment info. Enter your PIN, and you’re done.