A novel is fiction by definition.
I don’t agree that she missed an opportunity— no single novel is ever going to portray every aspect of an historical experience, certainly not without an even larger cast of characters. If her book was intended to be a nonfiction history of the Arab-Israeli conflict, one could criticize her narrow focus, but fiction is different, the writer gets to choose what story to tell. The story Alyan chose to tell is the impact of displacement— the Palestinian diaspora— over multiple uprootings, as it plays out psychologically over three generations. (She is a psychologist, after all, according to the dust jacket.) She chose to show us what it is like for one family who—like many. though not all, Americans—are professional, middle class, with homes and careers. They didn’t live in war zones with bombs, they were able to escape that due to extended family ties. But their resources did not protect them from loss. I can only speculate that the fictional Yacoub family was to some degree like the author’s as she was born in Palestine but is now a professional in NYC, that she chose to write out of personal experience. Other writers have written and will write, no doubt, about other perspectives.
She did try to bring in the wartime reality through the character of Atef, and what happened to Mustafa, and to the family of the radicalized imam, very early in the novel —maybe to show us why most people with the means to escape would have fled before they were physically driven out (if they did not choose to fight). She showed the impact of the conflict through Riham’s husband Latif, the doctor, and the victims he treated, how it radicalized her stepson Abdullah. It seems to me she was intentionally focused upon the inner conflicts of ordinary middle class people, maybe so Americans of the educated, book-buying classes could more easily identify, given that our national policies have more often been based on treating Palestinians as though they were all terrorists.
I understand from reading memoir and fiction about India, Africa and other places in the Middle East, that having a servant is fairly common for working and middle class families, there is a different economy and social structure than here -- more like the way it used to be here in the 19th century. It is more a reflection of how poor the poorest are, than an indication of the Yacoub family being wealthy. For an example, in "Girls Burn Brighter," by Siobha Rao, published earlier this year, a relatively poor family of weavers in an Indian village takes on a servant. Another example is in "A State of Freedom" by Neel Mukherjee (2017). Or in "A Thousand Splendid Suns," Khaled Hosseini.