According to Vincent Kauffmann, a professor at University of Lausanne and one of key figures in sustainable mobility, “free public transport does not make any sense.” Getting rid of tickets in mass transit is judged “irrational,” “uneconomical” and “unsustainable.”
However, if we turn to commentators from outside the field of transport, the perspective on fare abolition changes radically. Social scientists, activists, journalists and public officials—often speaking from cities where fare abolition has actually been put to the test—fervently defend the measure.
https://tribunemag.co.uk/2019/08/public-transport-can-be-free