Here's why:

* Topographic maps primarily focus on natural features: They show elevation changes, hills, valleys, rivers, lakes, and other natural landforms.

* Roads are human-made features: While important for navigation, they don't directly contribute to the map's representation of the terrain.

* Other human-made features may be included: Some topographic maps might include buildings, railroads, or other structures, but these are less common and often depend on the map's scale and purpose.

Important note: There are specialized maps that focus on human-made features like transportation networks, which would include roads.