But he will receive SS and his pension when he retires.
The government employees who do not pay the same into SS are paying into a government backed pension program-the pension isn't just a free benefit-money is removed every month from the paycheck. They will often not receive SS or receive a reduced amount of SS. They also generally have to pay their own private disability insurance because they would not qualify for SSDI if disabled.
Also, it's not like most of the beneficiaries of this program are high level politicians...you are talking about teachers, firefighters, police, etc.