On all the tours I have been on approx 12 since 2006 I have always left a review, unfortunately not EVERYONE uses this forum. Also a percentage of people once they get back the holiday to them the holiday is long gone and therefor they won’t bother.
All I feel we can do is when we away is to broadcast that this forum exists, so many people I have met have no idea of the existence, how valuable it can be and encourage other travellers to engage with the community boards...
It’s mentioned in brochures but word of mouth would help as well.
Cindy