The thing with trains is that they are naturally a monopoly, as there is a limited and set number of railways and train stations. Even capitalists often argue in favour of nationalisation of trains for this reason, competition doesn’t work where there is monopoly.
However, and this will also serve as a reply to the comment you left on my thread a few moments ago as we are talking about the same thing, barrier of entry is only a problem in the abstract. While it is certainly hard for a totally new business to start up into a market that has big players, it is not so hard for a big player to enter into a market with other big players. Consequentially, what often happens is that a business can grow in one field or one region, where the barrier of entry is low, and then generate wealth and expand, and then eventually enter into the new market where they otherwise would have been destructively priced out.
Furthermore the tendency of the rate of profit to fall, which I believe is what you are framing your beliefs on (correct me if I am wrong), is not necessarily guaranteed in an economy. It is a consequence of a point where technology can advance no further, so that increase in production can increase no further nor can efficiency, and consequentially the companies, having all reached this ultimate state of automation, now compete to cut costs as quickly as possible to beat the others. This, of course, is challenged as well. Rate of profit to fall doesn’t consider that there would be a basic consumer demand for a certain standard of product and that dropping below it would not lead to anger and demand for a higher quality product which would then be met by one of the competitors who was slow to cut prices, giving them the edge for so long as they retain quality.
It also does not consider the potential for infinite growth, or at least infinite opportunity for growth at any given moment. Batteries were thought to have once reached their limit, before being found to go to 10x the capacity some years later and revive interest in them, now they say the new limit has been reached, but how we different to say that now than we were when we falsely said it before? The battery example is true for many other areas. There may in fact be a point of technological perfection, but the chance of reaching it any time soon is highly unlikely.