And those materials are so entirely different from really anything else that engineers work with, particularly in how they fail. When you walk on the ground, you don’t really even consider that it can quote-unquote “fail” under load. In engineering, this means building wide concrete footings to distribute the weight over a larger area of the ground. But they don’t have a lot of strength, and more importantly, they don’t really engage with the layer above or below. Even in this worst-case material, there’s nothing even approaching the look of a washboard.