I was specifically talking about the days of the founders of quantum mechanics or even the times of Teller et al.. Today professors are in fact not that incredibly paid anymore in Germany. Sure they still have reasonably high salaries but compared to junior developers they earn approximately the same. Regarding PhD students yes depending on field, you might get a half position, however I'm not aware that postdocs get low paid positions. Compared to the US differences between professor and PhD salaries are much lower AFAIK.