While Bud, Not Buddy (by Christopher Paul Curtis) has a totally different feel (it deals with the Depression, but is not as unsettling as The Boy in the Striped Pajamas), it also is told in the "narrow/limited" THIRD-person point of view. It is from this style that some of the humor is delivered to a reader sophisticated enough to understand it.
In "The Boy", we see this when the narrator describes a talk he had with his mother in the dining room...
'Come downstairs with me,' said Mother, leading the way towards the large dining room where the Fury had been to dinner the week before. 'We'll talk down there.'
The reference to "the Fury" is a child's way of describing the "Fuhrer," or Adolf Hitler. The fact that the child's version of "Fuhrer" would make it seem like it is being told from the child's perspective, the story is not told using the pronoun "I." The narrator is omniscient in that he/she understands what is happening in the child's mind, but I believe the story is told in third person.
For instance, in "Bud...," the boy (Bud) meets Miss Thomas and believes she is the prettiest "human bean" he has ever seen. It shows the reader how children often don't hear things clearly or don't understand things that we assume are easily understood—but it is because we are adults.
This kind of writing, however, allows the adult to see the world through the eyes of simplicity as the world is seen by a child. This is also the same method Harper Lee used in To Kill a Mockingbird, allowing some of Scout's memories to come to us through very young eyes, while other recollections are shared with the adult Scout. Using a child to tell a story may rob the narrator of some credibility, but the honesty usually shown by a young narrator cleans away a great deal of clutter, allowing the reader to see through to the important aspects of the plot more easily. ("Mockingbird" was printed in the 1960s; Bud, Not Buddy was printed in 1999.)