Australian here: I think we have a cultural high degree of trust in our institutions. That trust is
frequently unearned or betrayed in the modern era, but it remains nonetheless.
I don't have a great definitive answer on why that's the case, but I do have suspicions. One is around the (perceived?) strength of our democracy, driven by mandatory voting and a well designed parliamentary system. Also, we don't have the American history of revolution - distrust for government just is not part of the thinking.
The other is that, for the most part of the last 50 years, our more public institutions have done a good job. The ABC (think the BBC, but Australian) is a trusted news source, Medicare largely "just works" for most people, our public/private education system mostly works, etc.
When it comes to law enforcement, I think the general perception is that while they're far from perfect, they tend to be well governed and as a result given a generous amount of power.
Again, whether this perception is justified or not is a different thing, especially if you're not of Anglo descent.