I think it would only be fair to put the cost of constructing roads next to that number since those are mindblowingly high as well. The first result I saw was that a 6 lane highway costs about $7-11 million per mile and that doesn't count the cost of all the cars that use it where as the first stat would count the train. I also assume that steel tracks last a lot longer than road surface which has to be rebuilt every few years. Also the cost of carbon emissions is often ignored in car price stats.