(a) The operator of a moped shall ride only astride the permanent and regular seat attached thereto, and shall not permit 2 persons to ride thereon at the same time, unless the moped is designed to carry 2 persons; any moped designed for 2 persons must be equipped with a passenger seat and footrests for use of a passenger.
     (b) The provisions of Article XV shall be applicable to the operation of mopeds, except for those provisions which by their nature can have no application to mopeds.