To elaborate, a central tenet of public choice theory is that some interest groups are better organized than others, and thus better able to influence the political process.
Indeed, this observation affords the standard explanation for protectionist trade policies,
which (perhaps with rare exception) lower the national economic welfare of nations that
employ them—the harm from protectionist policy is often borne by a diffuse group of
poorly-organized consumers, while the benefits inure to well-organized importcompeting
industries.
Not all industries are equally well organized either. Industries comprised of a
large number of small producers, for example, may have difficulty overcoming the
transaction costs and free rider problems associated with efforts to influence the political
process. Industries with a few larger firms may be better able to overcome free rider
problems and transaction costs, by contrast, and individual firms in such industries may
have high enough stakes in the outcome of policy decisions that they are willing to incur
the costs of acting alone to influence political representatives.
Thus, consider some generally applicable legal rule under a trade agreement, such
as a requirement that forbids regulatory measures that discriminate against foreign
commerce (the “national treatment” obligation in WTO parlance), and imagine that a
party to a trade agreement has violated that obligation. In the absence of any private
standing to enforce the rule, political officials in the nation whose exporters are
aggrieved by the violation must decide whether to bring a compliance action themselves.
If the violation affects a well-organized export industry, officials may expect significant
political rewards from such an action. If the violation affects a poorly-organized industry,
by contrast, they may expect few political rewards from bringing the enforcement action.