Retail card processors often charge a flat fee per swipe/tap/whatever in addition to the 1-2% percentage mentioned above. E.g., a five cent flat fee doesn't mat

Retail card processors often charge a flat fee per swipe/tap/whatever in addition to the 1-2% percentage mentioned above. E.g., a five cent flat fee doesn't matter on a $20 lunch, but it's over 3% of a sale for a single $1.60 donut. Perhaps more importantly, consider the following design document for donut transaction software a la Mitch Hedberg: "I'll just give you the money. You give me the donut. End of transaction."[1] Cash achieves this out of the box. You could have John Carmack and a billion dollars seed money and your cc terminal would still need to be rebooted in the middle of a transaction on at least a bi-weekly basis. 1: https://www.youtube.com/watch?v=xPq0-8dyl8I https://www.youtube.com/watch?v=xPq0-8dyl8I