A government operates under constraints that are different from that of an entrepreneur.
The entrepreneur has no choice but to satisfy his consumers by withdrawing from the market factors of production whose output, directly or indirectly, currently satisfies fewer consumers than they are looking to satisfy or currently satisfies less urgent needs than they are looking to satisfy. The profit they reap is a result of the improved allocation of these factors of production.
A government obtains goods in a different fashion. It needs to obtain them via taxation, which is in last resort an act of theft against the individuals within its territory. But individuals in general resent acts of aggression. In the long run a government can’t just send its police to collect taxes under no pretense whatever. Violent upheavals by the governed and subversion would inevitably ensue after some time. This holds true for a dictatorship as it does for a democracy. In order to justify its acts of aggression a government needs the consent of the majority of the governed, it needs public opinion on its side.
Which means it employs in order to attain this objective cannot categorically be determined. Throughout history, governments have employed different justifications for its existence:
Throughout history governments across the globe have always appealed to fear of foreign enemies to justify its necessity. But in addition there have been subtleties in other areas: In ancient days government leaders would be anointed by the clerical class which had the greatest influence on public opinion. During the age of enlightenment, with the appearance of capitalism, the idea of using government to protect private property and individual liberties became popular. When in the 20th century the concepts of socialism conquered the hearts and minds of the broad majority, the idea of complete government control of the factors of production had become unstoppable and was swiftly put into practice virtually everywhere in the world. When the attempts of socialism had proven impracticable and lead to the collapse of the Soviet Union, the ideas of interventionism convinced the peoples of the world of the necessity of government bureaucracy. Minimum wage, centrally planned welfare programs, fiat money and subsidies for special industries became the norm.
Thus the main constraint for a government is the approval for its actions by the majority of the people. It will always do its best to mold public opinion to the extent possible. So long as it confines its activity to the protection of individuals against aggression and theft no major harm is caused. As soon as it begins to embark upon broader expansions of its bureaucracy, those who are governed by it need to be ever more vigilant and doubtful.