First of all let me state that my total riding experience up here has been limited to (2) MTB rides.
I could see why someone visiting the U.P. would get the impression that the locals aren't concerned that visitors know where the trail is. My first impression would be that the locals have a small loyal, local riding community and they aren't concerned with outside apperances. (Again this impression is limited to (2) rides with Ishpeming locals) It appears that Marquette has formerly organized it's MTB community to make their trail system visitor friendly. I planned on going to Marquette MTN today and trying to ride that trail system without a local guide. I will write a post when I can get that done.
What comes to mind when riding with these men and women is "if it isn't broken don't fix it." These people ride together and make trails and share them with whomever rides with them. So, my suggestion would be if you visit, and want to ride up here that you ride with the locals. I would feel like a complete dumbass to suggest to these people that they put signs up and stuff. (I formed this opinion only after spending a couple of hours with them, 'I got it')
I did ask several riders about the MMBA, and they all sorta had a general idea of what the MMBA was... Then they would say things like "people up here aren't apart of the MMBA" and I would reply back "Yeah, because you guys don't join!" Then I say things like "You know, There are a couple thousand members..." I don't think it computes to them...
These people don't appear to have an agenda or any axe to grind, it's just that the community is small and the local government let's them do whatever they want. So, these people do whatever they want. Wouldn't you? So, why would you muck it up and get all nerdy with it, if you didn't have to? Makes since to me.
Maybe if I spent a couple years up here I might actually understand how it works up here. As for now I think I'll shut up and ride.
Ed