If at the age of 15-16 you haven't learnt proper manners and respect for authority or others, odds are that regular teachings won't work. As someone who lives in Australia, let me tell you that an overly tolerant police or judiciary system fails.
I doubt you were Mr Perfect when you were 15-16 years old. There is a difference between having bad manners, rebelling, respecting authority etc.
If you disrespect someone's request, that does not give them the right to throw you into an object and then hurl you across the room. This is not proper discipline. It is also a breach of authority, something that you seem to have ignored. You can arrest someone without using unnecessary force. I never said she should not be arrested. The force being used is over the top.
I am sure a simple arrest would have sent the message. You on the other hand seem to support unnecessary violence, which means you clearly have not learned good manners yourself if you think that someone who likely has not broken any laws should be dealt with in such a manner. Especially given that Australia is country that takes pride in giving people "A fair go". Abusing teenagers is not going to fix any societal issues, in fact it will create more issues because it will cause more people to resent authority.
If you were arrested, would you prefer the officer to still respect you as a human, arrest you without inflicting any harm, telling you your rights and taking you to the station for further questioning. Or would you prefer the officer to abuse you, and through you into the ground in a public place, causing further humiliation.
I mean, humiliating someone and infringing upon their freedom is a breach of human rights. Generally there are exceptions to this rule, like if you were to murder, steal etc. This student on the otherhand just refused to do as she was told for the most part. That hardly seems like it is necessary to infringe her rights as a human. Does the crime meet the punishment?
However you have implied, that using excessive force on a minor will fix society. Screw murder and those other serious crimes, if a teenager is being rebellious, they ought to be handled with no care, right?