Governments are not benevolent philosopher kings. Like everyone else, the people employed in government have incentives that may incline them to pursue policies that benefit themselves, but reduce economic efficiency and lower the overall standard of living.
The study of the economics of political decision-making is known as public choice theory. To provide the student with a realistic analysis of the economic impact of government action, some discussion of public choice is essential. Whether it is done in a separate chapter, or touched upon at various points when the subject of government arises, a good text will remind the student that the interests of politicians and bureaucrats is not necessarily the same as the "public interest."
A good treatment of public choice will include an explanation of voter incentives to acquire information, special interest group legislation, "rent seeking," and the reason regulatory agencies are often "captured" by the industries they regulate.
Texts that judge the marketplace according to rigorous standards must not easily approve government intervention merely because they believe it is motivated by good intentions.