Economical measures are hard to interpret, but they can give an indication: Japan GDP/capita is standing at 48,920 USD, and Australia at 56,919 USD. Germany is at 47,502 USD, France at 43,664 and UK at 42,986 USD. Japan is there, slightly ahead of Europe. Australia is somewhat ahead, but benefits from way more natural resources (minerals and oil). You can only grow fast so far: once your entire country is middle-class growth will be slower.
By comparison, Korea is at 26,762 USD, and China at 7,755 USD. These two countries have way more potential for growth, but also because they are way less developed for large groups of people. I forgot the exact salary difference for the same job between a chaebol and a small company in Korea, but I think we are talking 4x or 5x more at the chaebol.
Of course contributing to those fears was vast underinvestment in modernization by US firms which were still relying on very old and inefficient technologies, so of course to some stateside companies (and “pundits”) they looked like worldbeaters.