I guess to indicate the kids on the bus are retarded or disabled. Beats me. Ask BlackDog, he probably asked his bus driver why at some point.
Why I gotta take short bus and little brother takes long bus?
Why my seat so sticky?
Why my seat friend touching me in danger area?
Why it feels like rain in my pants?
These and many similar questions have all been asked at one point and one answer has been the default for all of them. A short gruff and a sharp smack to the face.
You're a great driver Q just not very good with kids.