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.
It depends on the proportions of your child's body, the shape of the vehicle seat, and where the seat belts are attached to the vehicle. Most kids need to ride in a booster seat from about age four until ages 10 to 12 years. Safety experts recommend that children continue to use a booster seat in the back seat of their vehicles until parents can answer yes to all of the following questions.