The reasons for this principle should be obvious. The demand for any good in the market depends on its marginal utility to buyers, as compared with its marginal cost—that is, the marginal utility of the money they must expend (pp. 4.6:7-9, 4.6:13-4, 4.6:34).

• If the service is provided by the government at no cost or at a price below the free-market level, then its marginal cost is thereby drastically diminished. Most commonly, of course, this cost must be borne indirectly in the form of taxes; however, that tax burden is shared among a large number of taxpayers. Consequently, the tax burden for a particular individual does not depend significantly on the quantity of the good that he or she uses—and hence is not part of his or her marginal cost as a consumer of the good.