It would seem that 'promoter' is a uniquely Indian thing. Thanks to this OECD briefing note, I learn that
An important feature of the Indian ownership landscape is the presenceof “promoters” and “non- promoters”. In principle, “promoters” denotesthose persons that were instrumental at the time of establishing thecompany and those who are in control of the company, for examplethrough shareholdings and/or their management position.“Non-promoters” refer to other shareholders, including minorityshareholders.
In India, promoters play a significant role in listed companies. Since2001, the average proportion of shareholdings by promoters has beenstable around 50%. Such a dominance of promoters could indeed bedetrimental to the interest of minority shareholders, if promoterspursue their own interests at the expense of the minorityshareholders. However, if the conflict of interest is well controlled,promoters could also bring benefits to the company by serving as avisible and informed owner, overcoming the agency problem. Thesecurities market regulator, SEBI, has also introduced policy measureswith reference to promoters and corporate governance. One example isthe requirement to maintain a minimum public shareholding, which wouldresult in an adequate free-floating stock, as the tendency ofpromoters to hold a higher percentage of their shareholdings for alonger period could harm market liquidity. SEBI has also strengtheneddisclosure requirements to safeguard the interest of minorityshareholders, including disclosure of pledging of promoters’ sharesand protection of minority shareholders’ rights in related partytransactions
Which explains why non-family-run businesses might typically have a 0% promoter holding.