Professor James Buchanan of George Mason University in Fairfax, Va., won the Nobel prize in economic science in 1986 for his pioneering work in public choice theory. It says there is little or no difference in individuals' motives in the various private and public spheres of action - essentially the same people act. They pursue their own interests rather than idealized versions of the public interest. The primary differences are the rules of the game, not motives, and therefore the incentives that individuals respond to.
Outcomes depend on incentives.
In other words, when a person becomes a part of government, he or she somehow becomes no longer self-seeking. But one should note that dressing a pig in a tuxedo does not change the fact that he is a pig. We should be realistic, not naive, about how government spending works. Federal funding inevitably becomes distorted because of special interest pressures. Every dollar spent by the federal government is received by someone.