(1) This part does not apply to an operator or passenger of:
(a) a motor vehicle manufactured before July 1, 1966;
(b) a motor vehicle in which the operator or passengers possess a written verification from a licensed physician that the person is unable to wear a safety belt for physical or medical reasons; or
(c) a motor vehicle or seating position which is not required to be equipped with a safety belt system under federal law.
(2) This part does not apply to a passenger if all seating positions are occupied by other passengers.