The Invisible Role of Ideology

Here is liberal economist Krugman debunking, yet again, the myth that public sector workers are paid more than private sector workers.  But what is really revealing about this way of framing the debate is the assumption--not challenged by Krugman (he is an economist, after all) or anyone else in the 'mainstream'--that the private sector market is the correct benchmark for compensation, such that a deviation from the private sector would have to be justified, or shifts the burden of proof of desert on to those who deviate.  But why believe that?  And why would Krugman believe that after only the most recent example of massive market failure, the Great Recession of 2008?