I feel like the elephant in the room with western society is that 90% of the corruption we have comes not from politicians but from the people themselves. People decide whether a policy is a good idea based on how it affects them personally not whether it is a good or a bad for the country or efficient or just. That's how you get a situation where (majority) mortgage owners are subsidised but (minority) renters are punished for example. The same applies to the justice system: people decide how they feel about court cases based on the victim/defendants age/sex/race/attractiveness.

So an AI either needs to ape those processes (and be popular but largely pointless as that is what we already have) OR to actually be fair but be too unpopular to ever be accepted by the people it governs.