For new rail at least, whoever wants to build them gets to own them, right?
I think what it comes down to is that if automobile companies had to build and maintain the roads, we certainly wouldn't have so many cars. But railway companies need to build the train lines, while competing with taxpayer funded automobile infrastructure. It's not impossible (see Japan) but also not easy.
It's rarely that simple. The question has to be asked "who owns the land?" because usually the rail lines get to belong to who owns the land, even if someone else builds them.
The interstate automobile road system got built through judicious use of eminent domain. That avoided all of these issues. Amtrak doesn't have the ability to do that.
I think what it comes down to is that if automobile companies had to build and maintain the roads, we certainly wouldn't have so many cars. But railway companies need to build the train lines, while competing with taxpayer funded automobile infrastructure. It's not impossible (see Japan) but also not easy.