This article should clear up any misgivings about how private transit companies would expand their networks. If the legal environment was such that companies could homestead land deep underneath others’ property, then I’m sure private enterprises would be building subways in every American city. That’s how it was in New York, back when the largest subway system in the world (after the Tube) was built entirely by private companies.
For the sake of our lungs and lifestyle, get the State out of transit. All they do is suffocate mass transit and build highways through our neighborhoods. Jane Jacobs, you should have been a libertarian.