How does Thomas Keneally use imagery in Schindler's List?

Imagery:

“Oskar knew people would catch that trolley anyhow. Doors closed, no stops, machine guns on walls—it wouldn’t matter. Humans were incurable that way. People would try to get off it, someone’s loyal Polish maid with a parcel of sausage. And people would try to get on, some fast-moving athletic young man like Leopold Pfefferberg with a pocketful of diamonds or Occupation złoty or a message in code for the partisans. People responded to any slim chance, even if it was an outside one, its doors locked shut, moving fast between mute walls.”