The debate around free-buses and transit has been often framed as a question of whether a person would prefer cheaper transit or more transit.

This framing is not actually economic - how much of a service we provide and how we fund it are two different questions. This pertains to all government services (parks, parking, healthcare etc). Fares (and lack of fares) cause externalities and those should be discussed. That's what recent economic research on Chicago showed - an optimal transport policy would set fares close to zero.