The stories in Hiroshima are stories of survivors. Hersey notes:
A hundred thousand people were killed by the atomic bomb and these six were among the survivors. They still wonder why they lived when so many others died. Each of them counts many small items of chance or volition--a step taken in time, a decision to go indoors, catching one streetcar instead of the next--that spared him.
When I watched The Pianist, I finally understood something fundamental about why people you read about (even in true stories) tend to escape miraculously and persevere through incredible hardship and so on. Simple enough idea, but I hadn't conceptualized it before: it's because the stories of the people who do not survive are shorter and less interesting--those people don't get to be the main characters--they don't "live to tell the tale." That has a great effect on our mythology, our literature, and ultimately on our collective character.