Pollies get to make the laws. They decide who sits on the High Court. They even decide who it is that establishes their entitlements and make their own judgements about whether or not they can claim for 'expenses'.
NO other public servant can do such things!
Further, as of the Treaty of Versailles in 1919 our colonial era Constitution became illegal and a fraud. That our pollies can so easily exploit it is further proof that our nation's government is as corrupt as many of those our pollies openly deride.