(a) No privilege tax shall be collected from any school bus operator or from any board of education for operating a vehicle to transport children to and from school unless the vehicle is used for profit in transporting other than school pupils.
(b) No owner or operator of a school bus used to transport children to or from school shall be liable for any privilege tax, other than registration fees for the bus, for transporting school children to or from any activity, during the normal school term, sponsored by or participated in by any public school or its students.