Some do. But consider some simple mechanics of it:
It you care about your legacy, and your opponent only cares about getting (re-)elected to benefit from the position, your opponent is at an advantage: Your opponent does not need to "waste" time, money and effort on things that does not improve their chances at (re-)election.
If doing the job IS wasting time, that means the incentives are all wrong. But still, who says that re-election is the goal? What about the places where they are limited to only 2 terms? How could re election explain ther second term actions? Or are people going to claim that at that point they're all captured by te industry using the revolving door?
It you care about your legacy, and your opponent only cares about getting (re-)elected to benefit from the position, your opponent is at an advantage: Your opponent does not need to "waste" time, money and effort on things that does not improve their chances at (re-)election.