Though it presents a close account of the aftermath of the nuclear apocalypse, Alas, Babylon maintains some crucial distance from its main characters.
Simply put, the novel is more concerned with the practical implications of the disaster than the emotional experience of its characters. Don't think this means we don't see any of the characters' emotional lives. There are plenty of times when there's real, raw emotion, such as when Dan Gunn tries to heal Malachai, with a need to save him "more than he had ever wanted to save anybody in his years as a physician" (11.126).
Rather, these emotions aren't the novel's focus.
What's more, the narrator will occasionally leave its perch inside Randy Bragg's head and give us a wider view of the world around him, such as when we're treated to Peewee's disastrous flight that kicks off World War II. Our heroes don't even know that this stuff is happening. Together, these two choices maintain the novel's focus on society as a whole, rather than merely one band of survivors.