This could be one line of research that may yield an answer.
Since the WTS shares are not publically traded then the current shareholders (those that attend the annual shareholder meeting) inherited their shares from family members long since dead. Is it likely that many of those that have inherited their shares are no longer JW’s themselves and so why would they take the trouble and expense to travel every year to the shareholders meeting if there was nothing in it for them? Does anyone know if a dividend is paid? How can one find out?