@joepie91 I am not aware of a comprehensive study, but I think Prague politicians have estimated fares cover about 15% of the cost of public transit (source: https://zdopravy.cz/litacka-za-7300-korun-prazsti-politici-sermuji-s-castkami-zdrazeni-rocniho-jizdneho-196061/).
Would love to see the coprehensive study, though
https://www.nymtc.org/movingforward/our-plan-to-pay-for-our-plan/index.html
6% of fees towards ticketing software, some of the "preservation" funds (likely 10%) would be for hardware to support ticketing, but uncertain how much. but at least it is a real number.
*note, most ticketing price systems take into account costs needed to cover maintenance.
@joepie91 I think Luxembourg has gone with mostly/all free public transport, so there might be research informing that policy.
Could be one for the #urbanism folks on here, too.