Bruno's father was a very high ranking official in the Nazi military. Therefore Bruno must dress in a specific manner appropriate to his station. He is from Germany, and, as such, must dress in a very disciplined manner. He wears trousers, shirts, ties, and socks and shoes every day. Even when he plays, he wears the same outfit. When Bruno asks Shmuel about why he wears the striped pajamas, Shmuel tells him that they took his other clothes away from him. He asks Shmuel if he didn't have a desire to wear something else, which is really ironic in that Bruno never wore anything else.
In fact he did like stripes and he felt increasingly fed up that he (Bruno) had to wear trousers and shirts and ties and shoes that were too tight for him when Shmuel and his friends got to wear striped pajamas all day long. (Pg 151-152)