The main obstacle in the U.S. is that the interstate passenger rail system was nationalized by Congress. Congress forces unprofitable long-distance routes on Amtrak and keeps the monopoly company undercapitalized. Amtrak owns amazing assets like the Northeast corridor rail lines, but there's almost no innovation as the monopoly loses billions of dollars and can't really tap private capital markets.
Meanwhile American freight rail-- totally privately owned and managed-- is the best in the world.
To be fair it was nationalized in the wake of the Penn Central bankruptcy and all of the other railroads wanting to drop passenger rail. Railroads were even able to opt out and I think a few did for a few years but it just didn't make sense to move passengers vs freight.
The actual problem was the federal Interstate Commerce Commission regulated routes and ticket prices and wouldn't give passenger rail companies the flexibility needed to compete with cars and growing air travel. Central planning failed and completely destroyed U.S. passenger rail.
Meanwhile American freight rail-- totally privately owned and managed-- is the best in the world.