Some critics have called the premise of the book and subsequent film – that there would be a child of Shmuel's age in the camp – erroneous. Reviewing the original book, Rabbi Benjamin Blech wrote: "Note to the reader: There were no 9-year-old Jewish boys in Auschwitz – the Nazis immediately gassed those not old enough to work." Rabbi Blech affirmed the opinion of a Holocaust survivor friend that the book is "not just a lie and not just a fairytale, but a profanation". Blech acknowledges the objection that a "fable" need not be factually accurate; he counters that the book trivializes the conditions in and around the death camps and perpetuates the "myth that those [...] not directly involved can claim innocence", and thus undermines its moral authority. Students who read it, he warns, may believe the camps "weren't that bad" if a boy could conduct a clandestine friendship with a Jewish captive of the same age, unaware of "the constant presence of death".
Kathryn Hughes, whilst agreeing about the implausibility of the plot, argues that "Bruno's innocence comes to stand for the willful refusal of all adult Germans to see what was going on under their noses".