It is unlawful for any person who has not been issued a license under this chapter to sell or keep for sale any alcoholic beverages; provided, however, that nothing herein contained shall be deemed to apply to those engaged in the sale of alcoholic beverages at the following locations:
   A.   State Liquor Stores: At the various state liquor stores;
   B.   Railroad Dining Or Buffet Car: In any dining or buffet car operated by any railroad in connection with regularly operated train service, when the person serving such alcoholic beverage is in the employ of said railroad is acting within the scope of his employment in doing so, provided a license has been issued to said railroad under said act by the Montana department of revenue, liquor division, and the same, or a duplicate thereof, is displayed in such car. (1975 Code § 5.08.110)