alt Hacker NewsCharge a small fee and those routes would be profitable on their own. You can of course add reduced/free fares for homeless/students if you wish, but most people can afford a fare and that money can go into running more service which the typical adult needs a lot more than the savings of a small fare.
Why be profitable? Charging fares on a free circulator is counterproductive. It costs to maintain and enforce fare boxes, and you’re adding friction to a system that’s designed to bring riders to the main routes. And you’re already running more service! The more successful circulators you have, the more passengers will be using the main system.