As a train nerd, I'm 100% on board with "nationalize the rails" and use a similar licensing system as we presently use with trucking and open up the rails to private companies whose equipment meets FRA + Amtrak standards.

With the rails being publicly owned railroads only have to foot the bill for vehicle maintenance much like truck companies do, and it puts railroads on an even footing with truck companies for price competition. There's always the challenge of investment in new lines, but that can easily be managed with a set exclusivity period, say "10 years exclusive rights for tracks you construct yourself" with requirements for maintenance, require FRA approval to remove the tracks within that exclusivity period, and require allowing non-competing passenger services and through trains (with of course very explicit language for what counts as "competing passenger services" since a once a week passenger car shoved on the end of a local freight train that goes from nowhere to nowhere shouldn't count as competing with hourly intercity passenger services)

With publicly owned rails, signalling and dispatching the FRA could also greatly improve throughput by eliminating a lot of the obsurdity that Precision Scheduled Railroading introduced (which is not precision, nor scheduled and its barely railroading)

Biggest for me is that publicly owned rails would allow for much more impressive excursion trains and more extensive routes that come much closer to home