[sien]

For people interested - Farebox Recovery Ratios around the world :

https://en.wikipedia.org/wiki/Farebox_recovery_ratio

In many parts of the developed world the ratio is 30% plus which can be an enormous amount of money. In Boston fare revenue is 500M .

Making things free would cause big issues for many of them as you say.

[Xylakant]

The calculation is not that simple, though. One expected effect is less car rides, which would require less car infrastructure and maintenance. That would also result in significant savings, car infrastructure is expensive.

[loeg]

Maybe in some holistic view of spending, but that isn't the reality of transit agency budgets. If transit saves DOT $50M, it doesn't go into transit's budget.