The global positioning system (GPS) uses satellites to send radio signals that can be picked up by receivers, allowing users to determine their precise locations. The U.S. military, which operates the satellites, originally excluded users by introducing errors in the information sent to receivers held by private individuals. The accurate signals were encrypted and thus available only to the military. In 2000, accurate GPS signals were made available to citizens. From an efficiency standpoint, should accurate GPS signals be available to citizens? Should citizens pay for the GPS signals? Should they pay for the cost of the receivers?