Although, in history, some nations have been ruled almost singlehandedly by dictators, most dictators could hardly be called benevolent. The assumption that governments behave as if they had a benevolent dictator may have developed out of the philosophical traditions of utilitarianism. Utilitarianism, whose roots date to writings by Jeremy Bentham in the early 1800s, suggests that the objective of society should be to produce the greatest good for the greatest number. In economic analysis we presume that individuals obtain all of their utility from the consumption of goods and services and this motivates the behavioral assumption that consumers maximize utility. The assumption that firms maximize profit is based on the same logic.
Profit affects the income of firm owners.
The greater one's income, the greater will be one's consumption possibilities and thus the higher will be one's utility. Thus profit is merely a means to an end, the end being greater utility. It is not unreasonable then, that if the objective of individuals, and firms, is maximum utility, the objective of a government might be to maximize utility for everyone. But, even if governments do not seek to maximize national welfare, it is still a valid exercise to investigate which policies would lead to a maximum. Indeed, most of the analysis of trade policies does just this.