I believe that even if government officials were free of special-interest influence and wanted to be pro-social, they would fail. They under-estimate their own ignorance, and in choosing leaders the political process selects for a lack of humility. Officials are prone to blunders, and the error-correction mechanisms are much weaker in the public sector than in the private sector. Markets tend to correct their failures. Governments tend not to.

Arnold Kling, Why I lean libertarian, Askblog