I don't believe you. In Massachusetts, state toll collectors make more than $60,000 a year. Try getting a cashiers job in the private sectore that even comes close to that. It's not the only example.
“I think the University of Michigan study must be working with aggregate numbers. The private sector number would include a whole lot of part-time workers at or near minimum wage at WalMart, Burger King, etc. Since the public sector is generally covered by “living wage” laws, etc., they can’t help but have a discrepancy.”
They - the private sector workers you mentioned - are also paying taxes to support the government workers, as many of those “temp” jobs are second jobs for working families and while helping them also takes the “family income” into taxable territory.
The fact is why should the average American citizen private sector worker be paying taxes to support levels of government employee benefits that they will never in their lifetime see. They shouldn’t.
Government employee benefits should not be part of collective bargaining. They should be set by law to be - skill for skill - never greater than the median in the private sector.
One reason many government salaries are as high as they are is phony pay scales; which I have seen directly in government job postings, where the tasks and responsibilities to be performed, as well as the skill and experience requirements are totally the same (in other words the job any applicant is being asked to do is exactly the same) but if the applicant has a higher academic degree they will be offered a higher salary - to do exactly the same job that can be done without that higher degree.
That rarely happens in the private sector, where, usually, if a higher degree is a requirement, then it is a requirement. If it is not a requirement for the work to be done then it is not a factor in the salary offered. Not true in lots of government jobs.