There is a very good standard economics answer to the question of whether public jobs overpay: You can't compare apples to oranges. However, you can compare how much folks want apples at $3/lb vs. how much folks want oranges at $2/lb. And you can compare how much folks want private jobs vs. public jobs at prevailing rates.
How many applicants per job? In the private sector, if there are too many, then the wage paid goes down, because you can get a good applicant for cheaper.
How much turnover? In most professions, people quit at some reasonable rate...due to the unpleasantness of the job. What rate do folks quit?
If those rates, which honestly measure supply and demand, are different between the government and private business, it's probably because the one with lower turnover, and higher applicant:job ratios is a better total compensation package.
Turns out that I disagree with Foseti an awful lot on an awful lot of topics. BUT...when he starts talking about what government employment is like, most everyone else ought to just shut up and read.