I agree, a lot of Australian television shows very heavy American influence, more so than actually exists on the street, I think, although, like elsewhere, there are regional and generational variations. In a truly serious piece of literate or historical fiction, you would have a lot of work to do - well beyond watching a few television shows.
But you're right. In comedy, children's or YA works an exaggeration is often fitting, even ideal. But if exaggeration is not your intention, then I still think it is better to go light with such characterisation than to go heavy but wrong.