Thanks for admitting you have no idea whether there is consistent nesting hierarchical structure in the distribution of vehicle characters. But in that case you have no reason to expect that they do. After all if you don’t know what to expect, then you don’t have a reason to expect a nested hierarchy.
People have, of course, attempted to sort non-biological entities into nesting hierarchies, and failed to do so. Carl Linnaeus famously tried to sort minerals into nesting hierarchies and failed. The chemical elements in the periodic table don’t sort into a nested hierarchy. The classification of stars(or planets, or comets, or other stellar objects) don’t form a nested hierarchy. Even designed objects deliberately forced into nesting groups, such as the folder system on your computer’s hard-drive, don’t actually form an objective nested hierarchy, as the attributes of the folders or files is not the criterion by which the nesting folder structure is derived.