The school bussing (at least in my area of the States) is provided by a bus company which contracts with the school district. The bus company in turn maintains

The school bussing (at least in my area of the States) is provided by a bus company which contracts with the school district. The bus company in turn maintains busses, and hires drivers (presumably?) part-time. They also provide bussing services for field trips, sporting events, etc. in addition to daily bussing to the school itself.