I would definitely vote for a politician that admitted they got it wrong. The problem they face is that such a big thing is made of it by other politicians and the media. They're accused of doing a u turn or being weak.
Politicians are human like everyone else, and they get things wrong, but we end up with the ridiculous situation of everyone knowing they've got something wrong, but the person responsible will rarely admit it as it's considered political suicide.
Its no wonder that trust is at an all time low, when the careers of the politician is more important than the good of the people they represent.