It depends on what kind of consistency we're talking about. Australian politicians from all sides of politics have rightly been lambasted for making seemingly absolute commitments to implement certain measures, or not implement them, then doing exactly the opposite once elected. Sometimes, this is for good reason – circumstances change, or new information is unearthed. But more often, it seems either that they never intended to keep their promises in the first place, or abandoned them when this became expedient.

Often it’s because they are trapped by the media or their opponents into making absolute promises they know they can’t, or shouldn’t, deliver: like “no new taxes”.

There’s also a fine line between sticking to one’s principles, and the compromises and accommodations necessary to actually get things done in government

Cognitive dissidence is very powerful.
All of us have it whether we acknowledge it or not.

Re phooey:

Ditto, self-pleasuring.

But we tend not to do it in public. Politicians might be the exception,on both scores.

I think its more an reluctance to change our conditioned beliefs and values even in the light of overwhelming evidence.
What's more we do not tolerate those who can transcend this negative tendency.