Paying with a plastic card. Or with a thumb. Your customers love it. But they want to be protected from fraud.
Checking the phone location against location of credit card usage can help. Customers feel much more confident, if they get real-time notifications when unusual activities occur.
Some micro-payments can even be triggered automatically based on arrival and departure in specific locations. Think about parking for example.
Insurance apps can even monitor driving behavior and give bonuses for safe driving.