Farmer John loads of basic errors in that.
Firstly public sector pensions are contributed to – you forgot to allow for that – I pay 9% from slaery and the NHS puts some in – I forget how much.
Secondly for jobs of equal skills / qualifications private sector pay is significantly higher
Thirdly you forget that the poorest of the privaste sector don't have pensions so you median figures are misleading.
Have a read of the link I put to the TUC site for the couter to the right wing propaganda you have swallowed without question.
The bottom line is public sector pensions are affordable and private sector companies get away with poor provision. Its not public sector pensions are unaffordablely good – its that private sector ones are poor – because in main of the greed of the shareholders and the pension holidays. Providing decent pensions hits at profits
I accept the TUC link is biased – but its worth a read all the same