"How can policy be improved? My first recommendation is that policymakers should pause and truly absorb the fact that government generally cannot be counted on to correct market failures efficiently by itself. Second, it is important for policymakers to acknowledge that the few microeconomic policies that have improved efficiency – which the federal government eventually grew to support – stem from market-oriented approaches." – Clifford Winston, Government Failure vs. Market Failure
Milton Friedman got it right, and Plato got it wrong.
That is the message that I take away from Clifford Winston's exhaustive survey of the actual results of well-intentioned government policies aimed at correcting market failures. He looks at policies designed to address all of the ills that economists and others have identified with markets – monopoly power, imperfect information, externalities, and so on. Government tends to make things worse, not better.
It's just a short little article, worth reading for the value of the lesson: trust not to governments. Remember what the late Harry Browne said: Government breaks your leg, hands you a crutch, and says you're better off.