Please don't tell me it's because they're "French."
From the American Museum of Photograghy
Eugene Appert: Execution of the Hostages at The Rocket Prison. Albumen cabinet card photocollage, 1871.
"..The photographer Eugene Appert made a series of pictures showing similar atrocities -- but only those committed by the forces of the Commune and not the bloody reprisals of the ultimate victors, the national troops loyal to Thiers. Perhaps if the fighting had gone the other way, Appert would have featured the crimes of the national forces against the Communards..."