I think the analogy does not hold. The reason these railroads are so well developed is because they lead to land the operator owns. If I apply the analogy, ISPs

I think the analogy does not hold. The reason these railroads are so well developed is because they lead to land the operator owns. If I apply the analogy, ISPs will develop infrastructure only if it leads to content they own. In other words, they have a strong incentive to throttle access to others' content, which is not an option available to railroad operators.