Or, dare I say, learn what they themselves were wrong about and become right about it.
We vilify politicians when they change direction and make them dance around and mince words, when what they really want to say is "I was wrong before".
We should commend people for updating their beliefs, not condemn. To me, one of the most honorable phrases one can say is "I stand corrected."
To admit they were wrong would be to say everyone who previously voted for them was also wrong. We don't have that much bravery from most of our politicians.
Editing to add: of course, the real reason nobody expects them to ever say they were wrong is because nobody trusts they actually fully believe what they say in the first place.