I'm not sure that the point that you make in the first paragraph could (or should) be elevated to the status of a principle. This case of Germany is peculiar in the sense that the preceding regime was deposed by external military force. Opinions on the success of denazification vary, although it is clear that many, many former Nazis managed to achieve positions in the postwar government. Still, many steps were taken to eliminate the residual power of the Hitler regime, and it helped that that regime had come to be closely associated with the crimes and atrocities of the Holocaust. A second key factor in the transition was the Cold War. The US, Great Britain, and France were actively looking for allies to help them check the spread of communism, and Adenauer was a canny enough politician to know which side his bread was buttered on. Integration into the system of anticommunist alliances was an important part of West Germany's collective strategy of rejoining the community of "civilized" nations.

Perhaps the most important difference is foreign intervention. The case of Greece's transition from authoritarian rule is not dissimilar to that of the Soviet Union. There is, as Laksos and Tsakalotos note, always a significant element of cronyism in capitalist systems generally. But both the case of Greece and that of Russia suggest that without some sort of countervailing pressure, the cronyism becomes inscribed in the structures of the resulting states. Capitalism can work a lot of ways, not surprisingly since it's about power in the first instance rather than money. The question really becomes: what sort of political environment is going arise in collaboration with the extant structures of local capitalism? German democracy is far from perfect, but it has at points in the postwar period been better (i.e. more responsive) than it is now. Both Russia and Greece are illustrations of cartel parties at their worst. In Greece the result is a layer of "technocrats" more interested in executing the bidding of the honchos in Brussels (and Frankfurt) than in responding to the needs of the Greek people. The question of how these processes might relate to the so-called Arab Spring and the political formations that grew out of it is an interesting one, although the difference in historical background and trajectory of the states in that region makes comparison extremely difficult.