Which payment method is NOT accepted for light rail tickets?

The correct answer highlights that personal checks are not an accepted payment method for light rail tickets. This is important to understand because typically, transit systems prioritize quick and efficient payment options to streamline the boarding process and reduce congestion.

Ticket vending machines and mobile apps are designed to facilitate fast ticket purchases, while credit cards are widely used for their convenience and speed. Personal checks, however, involve a more complex process of verification and clearance, which does not align with the need for rapid transactions in a transit environment. As such, personal checks are usually excluded from accepted payment methods, ensuring a smoother experience for passengers.