On ancient times, every work was made on relative bases as there was no conception of global systems.
It is possible to bring latitude and longitude for all terrestrial locations, but unless one has a highly precise GPS device or you make astronomical observations, this is impractical.
This way, the information describing each wheel can be simply duplicated four times, and independent transformations (e.g., steering rotation) can be similarly effected.
Local coordinates also afford digital designers a means around the finite limits of numerical representation.
In differential topology, local coordinates on a manifold are defined by means of an atlas of charts.