Or, more commonly, they have:

1. The public pay for and build the lines and prove market demand.

2. Decades later some 'fiscal conservatives' get elected.

3. Who then privatize them for a sweetheart deal to their friends.

4. Who then proceed to squeeze every penny they have out of the public, while foregoing expansion and service quality.

With an end result of everyone getting to pay through the nose for shit service, while profits accrue up. And nobody's building any competing lines, because rail is a textbook example of a natural monopoly, and it's hard to compete on capex with someone who got a full rail network by buying it, fully built out[1].

Nobody with a lick of sense will ever lend you the 100 billion dollars you need to open a from-scratch competitor, if you ever want to eat into the incumbent's margins. The incumbent knows this.

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The rail company is the poster child for either a crown corporation, or at most, a 'customer-facing services outsourced on a fixed-term-contract'.

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[1] Bonus points for rules around eminent domain changing at some point in the past century and a half, making it actually impossible to build a competing line today.