The crazy part is partly we don't know for sure why it costs this much in the every US project [1]. A deep dive into details shows a thicket of intertwingled challenges [2] that are solvable by goring an army of oxen.

[1] https://www.marketplace.org/2019/04/11/economy/subways-US-ex...

[2] https://pedestrianobservations.com/2019/03/03/why-american-c...