[Sharlin]

That makes no sense. They are subsidized exactly because the cost to society is vastly lower than having even more people drive their own cars. Every single person who takes the bus or train rather than adding one more car to the roads is making the society a favor. The point is not to make transportation purely market-driven – the market cannot efficiently solve that problem due to infrastructure being a) really expensive and b) a natural monopoly – the point is to balance the social and ecological costs of transport with the demand for mobility.