I taught at a rural school for many years. Several of the teachers also drove the bus. CDL license, training sessions with the highway patrol, criminal background checks, all required to drive a school bus in Missouri. One was involved in a wreck—not her fault—an asleep-at-the wheel driver crossed the center line and hit the bus. After all of the kids were evacuated and accounted for, she was tested for drugs and alcohol—SOP. I imagine each state’s requirements for school-bus drivers differs. I’ve heard that some states let high school students drive buses.
A CDL bus endorsement is required in VT. I was chair of the school board in my area and we ran our own busses. A criminal background check was a requirement for any and all district employees Teachers, administration and staff.
Back in 70s and 80s, students could get school bus driver jobs in SC.