Bus operators will often find it economical to convert retired buses to use as permanent training buses for driver training, rather than taking a regular service bus out of use. Some large operators also converted retired buses into tow bus vehicles, to act as tow trucks.
Explain to an 8 year old child that is not yet 49 tall that the safety equipment built into the vehicle is for adults  not children, and a child needs to continue to use the proper equipment (booster seat) so that the adult equipment will fit, and be able to protect, their bodies in the event of a crash.
Children between the ages of 3 and 4 who are at least 40 pounds are good candidates for booster seats as long as the lap and shoulder belt fits properly when the child is seated.The child should be able to sit comfortably for the entire trip without altering his position by sitting on his knees or leaning forward.