There is some merit to the trail pass idea, but should not be a hard rule. I have two or three of the maps. One is old, two are newer versions. Purchased the last one when I was last up in fall and had forgot my map at home. I don't mind paying $15 for a trail map that goes to help the trails.
The flipside is that many now use Trailforks, I would too, but have a Blackberry, so for now that is not a on ride option. Not sure of the model but I believe that in addition to working with the local trail association to ensure valid trails are shown, Trailforks also contributes to local trail associations.
All in all we are super lucky to be living in this area for the sheer volume and diversity of simply amazing mtb trails. I understand why some like trixie, noted above might feel protective, however riding with folks from out of the area or country and showing them a trail like Ruperts or countless others and seeing their stoke, makes sharing the trails all that much easier.