"Overall, research has shown that there is an overwhelming negative sentiment toward current digital tipping experiences and interfaces. 7-Eleven should leverage its larger mission, particularly the, "when, where, and how they want it," by enabling choice through an innovative digital tipping experience that shifts guilt and blame away from customers by creating a time-boxed response using one option tipping and creating proper defaults." — Tanner Williams, 7-11 UX Researcher
Including this self-service fuel pump asking for a tip.