PLU system is voluntary and based on business needs. It is not regulated by a governmental agency. Specifically, no regulatory body requires a PLU sticker on loose produce. Labeling produce with PLU codes are typically required by the retail industry to assist with point-of-sale (POS) identification. In various countries, most medium to large retailers expect a PLU as part of conducting business.
List of Commodities Not Required to be Labeled
Belgian Endive (Witloof Chicory)