Really, are all other scientific terms also subjective value judgements too. You know things like rate and speed and time and mass, those types of things. No wonder we have the theory of evolution when scientific terms are just value judgements.
Efficiency is a meaningless term when separated from ends.
For example, a motor that does nothing but cause vibrations is efficient for a hand-held massager, but very inefficient for a car. In the first case, the mechanism produces the desired end, and in the second it does not.
When someone calls cars "inefficient", and seeks government intervention for the sake of "efficiency", all they're doing is expressing a personal preference and trying to impose that preference by force on their fellow citizens.