Why is farebox return an important measurement? Roads aren't usually measured on toll returns - most have no toll at all. Consider that "All public transport

Why is farebox return an important measurement? Roads aren't usually measured on toll returns - most have no toll at all. Consider that "All public transport in Luxembourg (buses, trams, and trains) has been free to use since 29 February 2020"[1] - surely you don't think the lack of farebox returns makes public transport in Luxembourg "worst"? When you measure "passenger-miles per unit cost", are you including indirect costs? Because often these are ignored. For example, "Germany is considering making their public transit system fare-free in response to the EU's threatening to fine them for their air pollution levels." [2] Would that fine be included as part of the high costs of having a large car infrastructure? (Which also includes road building/maintenance, pollution, car crashes, zoning requirements for parking, and decreased physical activity.) [1] https://en.wikipedia.org/wiki/Transport_in_Luxembourg https://en.wikipedia.org/wiki/Transport_in_Luxembourg [2] https://en.wikipedia.org/wiki/Free_public_transport https://en.wikipedia.org/wiki/Free_public_transport