i still think back to the time i was bored enough to thumb through a translink (vancouver) annual report and found that fares accounted for like a third of operating costs (also advertising was a blip); worked out that making it free would be like $20 a month more in taxes (vs >$100 for a pass)

(this was in the wake of them installing their insanely byzantine fare enforcement infrastructure that they had to abandon a chunk of because nobody was tapping out of buses and getting dinged 2x+ and complaining)