Terrain features are much more of a constant than any man made features, especially trails. Even if they are depicted properly on the map (not always the case) they are moved, upgraded, etc. Sometimes not all roads or trails are even shown (think logging spur roads).

On the other hand, I used topo maps on the Channel Islands that were generated by the Army Map Service in 1943 from some of the very first aerial photogrammetry done in the US (Wonder why the Army was so interested in maps of the coast back then?). Even in 2000, the terrain was spot on, but the cultural features had changed considerably.