I have ask this question before: If a doctor can be sued for a bad decision/ bad outcome why are judges immune from the same rules?
Yes that is right...judges have immunity from prosecution. That needs to change.
If cops can be prosecuted and jailed for their actions, then judges should be subject to the same rules and laws.
Probably for the same reason that you can't sue members of Congress for anything they say on the House or Senate Floor.
Most legislators are lawyers by training. Passing laws that immunize their own kind (such as judges and members of Congress) just comes naturally. If most doctors also had law degrees, they could probably get in on the deal too.
Of course if you ask a law professor, you will probably get a philosophical/theoretical argument for the immunity. But as you point out, the explanations don't make much sense. If doctors are liable for their mistakes, it sure seems odd that ordinary people have to pay handily for the appeals process when a trial court judge has erred.