Authoritarian regimes and execution as coercion

From Plunder: The Cataclysmic End to World War II in Europe by by Max Hastings.  

In World War I, 150 German soldiers were sentenced to death for serious crimes, of which a mere forty-eight were executed.  In World War II, thirty thousand death sentences were decreed by military courts, of which two-thirds were carried out, in addition to many more that took place without any judicial proceeding.  By contrast the British executed forty men, the French 103, the Americans 146, almost all the condemned Allied soldiers having committed capital crimes as defined in civil law, rather than being sentenced for dereliction of military duty.  Meanwhile the Japanese executed 22,253 of their own men, and the Russians at least 150,000, possibly as many as 300,000.

I am currently reading The Greatest Battle: Stalin, Hitler, and the Desperate Struggle for Moscow that Changed the Course of World War II by Andrew Nagorski.  He notes that the official figure of 158,000 executions is almost certainly an undercount.  These were the executions which were adjudicated and documented.  During the desperate days in the fall and winter of 1941, as the Germans approached Moscow, and as the leadership of the Soviet Union teetered on dissolution, Soviet battlefield defeats were so extensive and retreats so prevalent that executions that many executions occurred without process or documentation or even recollection.