A gravel trail isn't there to make the user's life easier. It is there to prevent damage to the park. The gravel prevents people cutting a deep trench through

A gravel trail isn't there to make the user's life easier. It is there to prevent damage to the park. The gravel prevents people cutting a deep trench through the mud, which inevitably become a series of parallel mud trenches across the terrain. A gravel trail or even a pavement allows for more people to transit an area without doing damage. A ladder on the side of a cliff is just about making life easier and does nothing to protect the cliff.