How often do you find shelter registers missing, or pages torn out? Maybe it's more of a winter problem when weekenders use the paper to start fires. These past couple months I've found most of the pages torn from the Cosby Knob register, and no register at all at Icewater. Of course, these areas are heavily used by weekenders, so maybe it's not a real problem outside of national parks.
Also, who collects and replaces the registers?