we spent one zillion dollars over 200 years to make flat surfaces everywhere, often perfectly flat (like inside of stores), so that ball bearing wheels can work

we spent one zillion dollars over 200 years to make flat surfaces everywhere, often perfectly flat (like inside of stores), so that ball bearing wheels can work well. We've found that tracks work even offroad. Arms, sure, but why legs? Around a dockyard or a warehouse, a small tank with 6 arms might make more sense!