It's nice to have an opinion but free public transport causes many issues and isn't great policy, it actually means transport agencies have less money to invest and take out debt on as system use increases which is a very bad position financially. The same issues actually apply to roads as well and are a reason things like congestion taxes are a good idea.

So, explain why it works in 100+ cities all over the world?

Congestion taxes are completely different from ticket fees.

Fares typically make a negligible contribution to the overall costs of operating the system.

Public transport in the state of Queensland, Australia charges a flat fare of 50 cents. They only reason they charge anything at all is because they want the trip data for route planning purposes.

Free public transport solves many issues and is a great policy.

The notion that transit agencies need to be funded via fares is nonsense to begin with, but it looks even wackier when one looks at how roads are funded.