Istanbul, Turkey, has public transit like so many other cities. The way they manage it, however, is different from most. There is one payment system, using a stored value token called an iButton. It’s about the size of a coin cell and is typically hung as a fob from your keychain. Many stores have a terminal to put money into the iButton.
That’s different but might not be terribly special to Market Urbanists. What really matters is how Istanbul picks the bus routes. Ordinarily, cities both pick the routes and run the buses. In Istanbul, the city picks the routes, but any company in business can run on any route it wants. If there is a route that nobody runs on, the city runs their buses on it.
In this manner, everybody gets served, but no bus company gets subsidized. They all compete with each other on the popular routes, likely by bus cleanliness or spaciousness, since the fare is the same and the routes are standardized.