Environment key reason for fare-free public transport

First, the Environment set of goals represents the key reasons that initiated the creation of FFPT and they continue to be the main motivation for promoting this concept. Such a range of goals covers issues, which are closely tied to car-use externalities, for example, car accidents, traffic congestion, air and noise pollution, and the increasing dependency on cars. By abolishing fares, the municipalities are trying to encourage people, especially car drivers, to use public transport instead of cars (Storchmann, 2003; De Witte et al., 008; Zhou, Schweitzer, 2011; Cats et al., 2017).

http://humangeographies.org.ro/articles/131/a_131_3_straub.pdf 

Thorough study of fare-free public transportation

Free urban transit is a growing trend. In 2016, there were no less than 107 entirely fare-free public transport networks around the world, including over 30 just in France (CGTPAG 2016; Keblowski 2016).

https://www.metropolitiques.eu/Dunkirk-as-a-New-Laboratory-for-Free-Transit.html