I like the spirit of your analogy. The overall message is that, if something needs doing, and you see it needs doing, you doing it is the way to see it gets done fastest, and that if you recognize the need, then its getting done is something that benefits you, among others.
There's an important difference, though. There are no rangers in this park. No one's employed by the park to get something done. Maybe someone's employed by one of the office buildings next to the park because they want nice scenery. But the park itself has no employees. So if no one does something, it simply doesn't get done. Perhaps a better analogy is a remote sparse community in mountain or wilderness areas, where there isn't much in the way of government oversight and public works. If you need a bridge over a chasm, you build it or there's no bridge. If livestock need a well, you dig it or there's no water. Anyone who stands around waiting for something to get done is likely to get (a) very hungry, (b) laughed at or (c) shot by someone who's struggling to do it for himself. This community is probably somewhere between the two.
