[anamax]

Isn't effective government a system which can maximise the following function?

almost certainly not.

For example, many people think that "effective govt" involves some notion of "justice" and/or "fairness".

One concrete example is Obama's position wrt capital gains taxes. He wants higher rates even if that results in less revenue. (Higher rates with less revenue means that there's less capital gain, which means less wealth produced, aka less total stuff. Since there's less tax revenue, there's less govt spending.)

A significant number think that "effective govt" propagates certain values/behaviors and discourages others.

Yes, there is disagreement on what "justice" and "fairness" mean and there's also disagreement as to the values/behaviors to be encouraged/discouraged.