I do a lot of mountain bike trail mapping work using OpenStreetMap, and it's really bugged me that more public-service mapping projects (eg: MTB Project) don't build on OSM. They all tend to instead build their own mapping set which requires stuff to be re-entered... It's kind of a pain.
I don't know whether there's anything which could be done to help these more corporate charities get on board (for instance to make it easy for them to set up and maintain an official database using OSM tooling, on the basis that the data they gather is publicly available and licensed as open data).