[math-fun] hiking v. computer generated images

Mandelbrot's book had some pix of fractal "hills that never were". If you do a Google search for this phrase, Google will show you the actual pictures from Mandelbrot's book. My problem is that these hills are not as "hikeable" as real mountains, so something is wrong with this picture (or actually, the model generating the mountains). If you hike a lot, or if you stare intently out of airplane windows while taking off or landing in mountainous areas, or if you spend a lot of time with Google "Earth", you notice that there are a lot of trails & roads on mountain "ridges". But there aren't any ridges on Mandelbrot's hills. Where did they go? What's wrong with the model?