Pret a Manger fast way to pay?

Hidden amongst the tempting treats near the tills of pret a manager is a quick pay method. The method involves scanning your credit/debite card over the unit. This saves the slightly slower method of chip and pin. However I am unsure of comparability with cards? Are cards now regularly used in comparison to cash especially on smaller purchases of items. The future of easy/convenient paying in this way may not be the safest for bigger amounts of orders.