And how exactly did you divine that fact? I know of no way to tell whether an interstate is profitable or not because there is no way to do economic calculation. That is the heart of the problem. People aren't directly paying for the product and we have no way of telling what the external benefits are. A private company would have people pay directly for the road and would internalize any externalities they create. We would easily be able to tell whether or not such a project is profitable. Can't do it with government. Surely roads would be profitable if run by private companies, but not with our current framework of subsidized alternatives.
It really depends on travel and cost. Some roads can be profitable, some wouldn't be. Just because a road isn't profitable doesn't necessarily mean it shouldn't exist. There are plenty of reasons for having a very sophistocated and expansive structure. A private company folds, what happens to the road? Gets sold off, falls into disrepair, there are lots of negatives from having private companies own something like the roads. It's like the post office, it doesn't have to turn a profit; it just needs to be there. Because private business is subject to many varying winds and circumstance, the government is more robust. I understand the appeal of thinking that roads should be privatized; but I don't agree. There are far too many concerns which go along with it. Once something is established, then yes it becomes easier. For instance, private companies can buy sections of roads. But the initial backbone, the initial structure had to be conquered through the use of government first.
How long does it take for an oil company to receive a profit on the drilling it does. I can take 30 years for an offshore oil platform to start producing, yet oil companies do it anyway, don't they? How long does it take for a skyscraper to become profitable? How long does it take for a typical mortgage to become profitable! Yet it happens all the time. People take huge losses at the present for gains in the future. To deny this fact is to deny reality.
There's a lot of money which goes into prospecting for oil. That's why YOU can't just get up, get a loan, and go out and do it. There are already established oligopoly which exists now, and the barrier to entry is exceedingly high. These companies also share a lot of government protections, subsidizes, and privilege. Hell, there was supposed to be oversight which turned out to be cocain and hookers. Oil companies are not really a good example because they are heavily funded and supported through various government means. In fact, there are a couple whom own large hunks of land they are sitting on. And while they are sitting on it, they're making bank from the government by not farming it. They're just sitting around until it's profitable to mine the land for minerals.
No one has been proposing that one company would build an entire national system. There would be a mosaic built by many smaller companies each contributing their part to a national system (most likely).
So will there be standards then? Or is each company going to make their own sets of rules? Where are they getting all the money from? You can bet your bottom dollar a good portion isn't going to be just loans from banks, etc. The government is going to be there, funding away as well. What about land concerns? That can be incredibly expensive without the power of Emminent Domain.
No, the best thing is to create it all in a single plan. While plenty of private industry will be brought in to construct it; an overall plan with rules and regulations set for the transportation means is well better than breaking it down in completely different companies. High speed rail isn't something which is highly benefitial going 20 miles. It's benefit really comes in on longer trips. Which is why you want to hook up cities, particularly across State lines. That's the government's business right there.
Again, oil companies and financiers do this all the time. Why are you conveniently ignoring them?
They do it because A) They are founded. It's easier to do something once something exists. It was pretty easy early on to break into oil (once the monopolies had been dealt with), and before when there was proper oversight and regulation to prevent oligopoly. Now there are only a handful of companies out there, and they are established and the oligopoly in place has created a barrier to entry to ensure that they are the only ones around. They recieve tons of money from government, and they are pumping oil which is hella profitable. Saudi Arabia, for instance, pulls oil out of the ground for about 5 bucks a barrel, and what's the going rate these days? Oil is known to be profitable. Which right there is the major difference between giving money to oil companies whom you know will turn a profit or funding a high speed rail to which you have no idea what the return will be. People need oil, it has to be found, it's exceedingly profitable, there are only a handful of companies with the resources and capability of doing it. And that's why they can "do it all the time".
Thus your appeal to oil is no applicable to high speed rail since the conditions are wildly different.