It’s an interesting the gradual technical changes, from bullets to gas to bombs to depravation of water. They must measure big improvements in efficiency, measured in number of deaths per dollar and per day. Imagine of a report from a recent study on this got leaked!
For private business the tickets are to fund the business. But for public transport they are never expected to cover the costs of the business.
It is run as a public service, not to make money. The function of tickets is to prevent overcrowding.
That’s why in well designed systems, the price is different at rush hour, and for high traffic routes and times.
I don’t know anything about montpellier specifically though.