I liked how it wasn't explained because the goal is to make you think about those questions. In a post apocalyptic wasteland where valuable resources are scattered far away in an endless desert, wouldn't cars become an almost mythical and religious item? Without the Chrome Cars, everyone would die as they would be unable to travel and get food/water/etc. So is it any surprise that after generations of living like that, they would worship chrome much in the same way primitive cultures worship the sun/rain/water?