Here in the states, yes. But who knows about Australia. They just gave a guy who murdered his wife a year in jail, so they sound a bit more lax than the cops here.
In my jurisdiction we can. We have ordinances about being able to hear music fifty feet from a vehicle. It is extremely rude and moronic to think that other people want to hear your music. If they did then they can listen to it on their own in their own vehicle. I write people for this violation all the time.
I have never seen a pig or other barnyard animal stop anyone for anything. I don't think they have any authority to enforce the law.