It still was not the "norm" on the western front. Most prisoners taken actually came home. Execution was the exception, even at the hands of the SS.
The story on the eastern front was much different, and while there were mass executions there, the specific policy was to immediately execute political officers as a matter of course. Others were mostly starved and worked to death (much of the blame for that can be laid squarely at the feet of Stalin and his refusal to abide by Geneva Convention but that is another topic). Those who could not keep up with forced "death marches" were executed as a matter of policy.
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Colonel Erwin Lahousen, a German foreign intelligence officer, wrote in October 1941 that "The columns of [Soviet] prisoners of war moving on the roads make an idiotic impression like herds of animals. The guard details ... can only maintain some semblance of order ... by using physical force. Because of the physical exertion of the marches, the meager diet and poor conditions in the quarters in individual camps, prisoners of war often break down [see photo above], are then carried by their fellow-soldiers or are left lying. The 6th Army has given orders that all prisoners of war who break down are to be executed. Unfortunately, this is done on the road, even in towns ..." (Quoted in The Hamburg Institute for Social Research, The German Army and Genocide: Crimes Against War Prisoners, Jews, and Other Civilians, 1939-1944 [New York: The New Press, 1999], pp. 100, 142.)
Below is a photo of an open air POW camp full of Soviet prisoners in 1941. No doubt most never came home, dying of starvation while in the hands of their captors.
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