The occluded objects dont cast shadows. The shadows I used here dont have such a long distance. Maybe it occludes the terrain textures/shaders per pixel as well. I am not the one who programmed it. But it is no shadow. Unity switches real-time shadows off in a distance.

And maybe you did not know but in the blog of the Unity makers they admit that shader writing was too complicated in the old version and that they will make it way more easy. We will see what that means. But for me it is ok, I have everything that I need in the moment. And then there are still enough additional ones in the Wiki.