In the U.S. Postal Service there is no straightforward mechanism to correct problems or force the agency to change. No citizens can own tradable shares. The income and security of managers and workers are guaranteed by the monopoly on first-class mail, public funding and the employees' political clout with Congress. The public cannot shift its business to more efficient competitors, because competition is prohibited. Consequently, the gross postal inefficiencies are not the result of the character or personality of the individuals who happen to occupy positions and jobs; they stem from the structure of the Postal Service itself. 
--Douglas K. Adie, "Privatizing Will Improve Mail Service Posthaste," 30 January 1995