Questions to Models of Public Goods Supplied by Traditional Government

Government's main function should be providing the public goods,but the public goods actually by no means would only be provided by the government.There're many difficulties exists in providing public goods by government directly,such as government's economic man characteristic,limited rationality,information asymmetry and how to deduce society's wel-fare function from individual utility function and government's low efficiency.Meanwhile,government's low efficiency which arose from lacking competence system and supervision and features of multi-agent is difficultly overcome.