Why do so many Australians seem blunt and lacking in basic manners?

Why do manners seem to be less common in Australia? It often appears that many people lack basic manners, common courtesy, and respect for others. Some Australians can come across as blunt, rough, or lacking in refinement and social grace. While this is certainly not true of everyone, it can create the impression that standards of politeness and respect have declined. Since courtesy, respect, and good manners are important principles of any civilised society, why does Australia sometimes seem to struggle with these values?
Why do so many Australians seem blunt and lacking in basic manners?
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