The same approach seems to be taken by everyone who deals with the public, from customs officials to hoteliers to shop assistants. There are no circumlocutions like "would you mind if....?" or "could we possibly...?", or "we'll be just one moment" or whatever. There is a no-nonsense approach with a to-the-point tone that is direct to the point of seeming abrupt. The rising end-of-sentence tone that comes with the Australian accent means you're not quite sure whether what's being said to you is a question or a statement anyway, and this just adds to the sense of disorientation.
So after a couple of routine questions about your name and address, you are totally convinced that you must have done something terribly wrong. The brusque approach means that everything is done in no time, though it feels like forever as you turn over in your mind just why it could be that you are being spoken to like this. Then the questions come to an end and Official Person looks you directly in the eye, so you conclude that you are in the worst trouble ever.
You wait for Official Person to say "You're under arrest," or "Stay there while I call the police," and reflect on the fact that by now you would be willing to confess to absolutely anything. And Official Person's unwavering glare continues to fix you to the spot, as you hear the final fateful words: "Have a marvellous day, Sir." Or, "Welcome to Australia," as appropriate. It's in the same firm tone as before so you have no doubt about its sincerity. In Britain or America, "have a nice day" sounds like bullshit. In Australia it feels like a self-fulfilling prophecy.
Important note. Mark wishes it to be pointed out that he wrote this passage before he was run in by Victoria's traffic cops. However, he also wishes it to be known that his experience with said officials has not altered his view that such people are humane, reasonable and understanding salt-of-the-earth people. Who let him off. What sensible types they are.