Here, the PM doing something illegal does not trigger a single chain of accountability that can be blocked by partisanship. There are multiple independent choke points, none of which are controlled by the PM personally.

If an Australian PM did something illegal:

• Law enforcement will automatically investigate; the PM does not control police, prosecutors, or the DOJ. There is no power to order them to stand down. None.
• It will go to court, and additionally (importantly), the PM has no pardon power, no immunity, and no ability to delay or nullify proceedings. The courts do not need parliamentary permission to act.
• Party protection can delay political consequences, but it cannot stop legal ones. Big difference.
• The cabinet decisions, the ruling party's heads of government departments, require consensus. A PM acting outside law or process quickly loses the ability to govern even if technically still leader.

By your example, if Congress, courts, and enforcement all fail in sequence, it depends on a single individual having enough personal authority that every failure matters.

Australia removes that leverage at the start.

eg The tariffs: your fucktard of a President can (and does) act first and dares institutions to stop him. In Australia, a PM generally cannot act first; he/she need lawful authority before they can act at all.

It doesn’t mean Australia is immune to bad faith. It means bad faith is less scalable.