On average, Australian culture views anyone, who even passively demonstrates any significant level of achievement, with a high degree of suspicion. Australians make a national sport of cutting down people who excel in any way. Sure, there are sub-cultures there which can vary considerably from this general trend, but even they feel the influence of this prevailing attitude. The end outcome is that Australians tend to go to considerable effort to hide the things that may single them out as excelling among their peers, and emphasise those things which make them similar. (A few months ago the CEO of the most powerful retail company in Australia gave an interview attempting to reduce public ire at their price gouging tactics, dressed in the uniform of a shelf stacker from their supermarket chain. I'm not saying this could not have happened in America, but there it would have probably been seen as a stunt or a statement... in Australia dressing any other way would have raised eyebrows, and in fact most people initially failed to even notice it for the PR manipulation that it was.)
Geographic proximity will always play a role in bringing cultural norms together, and while the US is a big place, the US population throughout the 20th century had incredible mobility, going where the jobs were, which helped to tighten up that bell curve.