I'm watching clips about Auschwitz and I can't work out why in the middle of a war you would transport 100's of thousand of people to die? It seems a lot of effort when you could make local arrangements. So why did they do it?
They needed large facilities to process the bodies and all the possessions. They also wanted to keep it somewhat secret.
More efficient would be my guess. Why would you build a bunch of small camps, that would take more people to maintain, when you can build a few big ones, and haul them by train. If your next question is, "why not just shoot them?",bullets cost money, starving or working someone to death a lot cheaper and if they work you get something out of it.
It was part of a system to kill as many people as possible. If you attacked the people right there, they are more likely to fight back and resist, hide valuables, etc. Instead, they lied and said they would simply be relocated.
1) Germans are known for their efficiency and preciseness. Everything must work like a machine. Centralizing the extermination effort was the most efficient way. 2) Keeping it secret. Jews were promissed to be taken outside of the ghettos and away from the discrimination to jobs and a better future. And when they arrived at the camps, even there they were lied to to get them to go into the gas chambers. "Take a shower please."
