Have you seen public sector pensions? They are exorbitant and funded by taxpayers who have no hope of seeing similar plans. How is this fair?
Because the idea was that public service was a trade-off from private sector work-a lower salary, but higher benefits and more job security. It attracted people who believed in the mission of the public sector (something that conservatives, btw, don't really believe in), didn't only care about making money, and was meant to retain that talent.
For a long time, it was successful. But, for a variety of complex reasons, the public sector has been the victim of a successful attack from free-market demagogues in the private sector, who have promised to make the public sector more "efficient" and "responsive to the people", but have really just made the government the instrument of the biggest players in the private sector.
The real question is: why is the private sector becoming so abysmal? Why subject the public interest to the whims of the free market? That's always been a horrible idea, and remains so to this day.