There s a whole world built vaguely along human lines, but inhabited by cars. Who built it? Why do they need towns? I like to think that there s a whole Planet Of The Apes subplot which will be revealed one day where humans built hyper intelligent cars who eventually overthrew their masters and then proceeded to remake society along the only lines they knew how human civilisation. Leaving us with a mockery of our own world. A lot of people also think they re being clever and ask how they reproduce, but that s a silly question. They get made in factories. However, the very best solution to this plot hole can be found in the Pixar Theory. If you ve yet to have the pleasure, I suggest you make a cup of tea and look it up.