make it hard to collect payment from all the potential beneficiaries-for
instance, the large number of people who profit, albeit indirectly, from
advances in basic science;
make it hard to collect from the beneficiaries of consumption the true
economic cost of making use of the -g ood or service-fresh air rhar vehicle
owners use as a sink for their auto emissions;
make it hard for consumers (and sometimes suppliers) to know the true
qualities of the good or service they are acquiring-many repair-type services,
including those performed by physicians as well as those performed
by auto mechanics;
make the cost of producing the marginal unit lower than the average cost
within the relevant range of demand-a magazine article distributed via
the Internet.