A. Except as provided by Section 66-7-369 NMSA 1978 and in Subsection B of this section, each occupant of a motor vehicle having a gross vehicle weight of ten thousand pounds or less manufactured with safety belts in compliance with federal motor vehicle safety standard number 208 shall have a safety belt properly fastened about his body at all times when the vehicle is in motion on any street or highway.
B. This section shall not apply to an occupant of a motor vehicle having a gross vehicle weight of ten thousand pounds or less who possesses a written statement from a licensed physician that he is unable for medical reasons to wear a safety belt or to a rural letter carrier of the United States postal service while performing the duties of a rural letter carrier.