Mexico toll road discussion?

In the US or Mexico - roads are roads and costs are costs. Most Interstates in the US are toll free and paid for with taxes. A few roads in the US were turned over to private companies. In Mexico they theoretically turned the roads of to private companies so those companies would carry the cost of building and maintaining the roads because the Gov't could not afford it (supposedly). So companies intentionally made bad investments as a write off? The Gov't that claims it has no money is paying the companies to run the roads? The companies that make no money on the roads pay the Gov't so they can run roads that make no money? I do have a pretty good understanding of how some things work in Mexico. And I am not asking them to reduce tolls for me. I am trying to figure out a basic - supply and demand - build roads that few will use and operate at a loss because they charge too much for people to afford to use them? I am not saying all the roads - and I am not sure who operates which roads and how each road is paid for. So there are obviously roads that do pay for themselves. But with all our travels in Mexico it is pretty clear that some of the roads with the highest tolls get very little use. I can hardly believe they can pay the workers let alone paying off building costs and keeping up maintenance. Yet new roads continue to be built and they continue to charge high tolls. I know that some say there is no way to find logic in what goes on. I know that. But there has to be money from somewhere yet from what we hear and see there is no money. Any logic says there must be money to build a road and then to pay for it - and to maintain it - and to pay those who work on it. Yes, I know I should not try to make sense or find logic in what goes on. I am asking if anyone has any facts about how these roads are paid for - maybe the deal with the gov't is that if the concessions do not make money then the gov't subsidizes? Does no one anywhere - CAPUFE - SCT - whoever - have any sense? I think I will back off this whole discussion since it really is not a discussion I can make sense of. Perhaps someone who has some facts to present can jump in and explain some of this. Until then I am off this topic.