Public transport, however, is a public good. It is also too expensive of an investment (at least when referring to subways and light rail) to generally be something a private company could do. There is also a measure of fairness involved. Or would you say that people living in rural areas should not have gotten electricity or telephones?
Farm subsidies are tricky. The most outrageous like cotton are a result of concentrated political power. Others have benefits to the public good, like a secure food supply or maintenance of the land.
To deny that there is such a thing as the public good is absurd or anarchist. The environment is a public good. Pricing SOX, NOX or CO2 is just a matter of internalizing previously external costs. The market then has to work to minimize those costs.
Water used to be free, until there were too many people. One used to be able to go out in the woods and hunt or fish as much as you wanted. When these goods became scarce they became regulated. It is a natural progression.
I agree that command and control are the things to avoid. For the government to say who, what and when something will happen rarely if ever works. For the government to make the (least amount of) rules deemed necessary and let the players figure out how to best play the game is common, conservative sense.
The "public good" is an overgeneralization of several rights and a lot of socialist junk. I have the right to clean air, CO2 doesn't make it dirty. I'm sure we've argued this before, but AGW is based on models that primarily use water vapor to warm the earth, CO2 only contributes a degree or two. If you insist on defining a "public good" then define it as a function of model output, then I can pay to have SO2 injected into the upper atmosphere or some other equally cheap solution to warming (if it is indeed a problem).