if you read the book KL a History of the Nazi Concentration Camps you will have a good idea of why people had to have known, no question.
it’s a depressing book, of course, but it’s thorough.
It’s easy not to “know” what you know to be dangerous to know. The whole point of the original concentration camps like Dachau was to instil fear and terror of stepping out of line, precisely enforced by telling people who were taken in for a short initial time, and then released, that if they ever revealed what had happened to them they’d be back for worse.
The moves to concentration in ghettoes of Jews, forced labour for them and other prisoners, and ultimately extermination, were all provided with official cover stories, to the extent that they were in the public domain in the first place (don’t forget, no access to foreign media, except on pain of severe punishment, even if you retained a radio capable of receiving foreign stations, which a lot of Germans, maybe most, didn’t). So it was hardly a problem to persuade yourself that if the people two doors down suddenly aren’t there any more, they’ve just gone away to live and work elsewhere. Terror tactics against civilians on the eastern front wouldn’t be openly discussed as such, or dismissed as “fog of war” or dealing with Bolshevik terrorists.
Of course, there were plenty of people who’d heard stories from relatives and acquaintances in the forces who were on leave, and information did get out to the Allies by various means, but that would be anecdotal and capable of being minimised as exceptional, even where people took the enormous risk of gossiping about it. But the notion of planned and industrialised mass murder was hard to grasp even for them. I found the memoirs of Christabel Bielenberg (a British woman married to a Berlin civil servant, and involved with anti-Nazi conspiracies) instructive: she understood the Jewish deportations meant nothing good as they were happening, but she didn’t understand exactly what it meant in practice till almost the end of the war when in the darkness of a train stalled in an air raid, a sick SS officer just unburdened himself and described the things he had seen and done, irrespective of who might be listening.
Inside the command structures, of course thousands of people knew and understood what the Holocaust was all about, but even they were somehow capable of euphemising it all to themselves if they weren’t actually there. At one museum in Berlin, I saw a letter displayed that had been written by a journalist for an SS newspaper (and therefore holding an SS rank) to his superiors, protesting about the open brutality of guards towards Jewish deportees in Berlin, under the windows of his office in front of his staff. Hard to judge whether it was the fact that it upset the typists or that it was inherently wrong that he was protesting about, but he did say something along the lines that surely it was possible for the guards to behave with some humanity… make of that what you will.
I agree, and even if they were doing so via subsidiaries during the war, it doesn’t necessarily mean that they were aware of the uses of the tabulation machines as far as the Holocaust was concerned. Most of the West was relatively unaware of it- especially as you got out of the high echelons of political and military command.
Not just ‘relatively unaware of it’, the mass executions at concentration camps didn’t start until just after Pearl Harbor. I’m not sure of exactly when IBM would be cut off from it’s European subsidiaries, but I don’t think there’s even a month between ‘any mass killings at concentration camps were happening’ and ‘Germany was completely embargoed and IBM had no more communication with its continental subsidiaries’. Plus, again, governments keeping census data is not actually a controversial action.