In the book Night what was NOT part of Hitler's three-fold plan to rid Europe of Jews?
The main reason is that they didn't want to know.
We discussed this in GREAT LENGTH in my English class, and here was what we got.
Yes, someone actually warned the town, but the guy who came in to warn everybody, Moishe the Beadle, wasn't all that influential. He was a "jack-of-all-trades" (meaning he had no real skills so he dabbled a bit in everything) and "lived in utter penury" -he was dirt poor. Look it up, it's the first page. Anyways, what would you do if the town bum came in and told you to pack up your comfortable life and hit the road because the sky was about to cave in? You would probably stay put too. That's basically the situation we have here. Moishe was without proof of the horrendous Nazi crime, and the Nazis themselves weren't exactly announcing their goings-on to the world.
And it's true, "they didn't want to know." Whatever chance the town had of hearing the truth in Moishe's warnings was dashed at the feet of their own reluctance to hear it.