Mexico toll road discussion?

The questions I am asking are based on the story about Indiana - not enough traffic means less revenue - high tolls cause people to take alternate routes. In Mexico we see very lightly used toll roads charging very high tolls. I cannot imagine any of them can get rich if very few vehicles use the roads. So would it not make sense to lower tolls to the point where they would get more traffic and thereby get more revenue. It seems there is an idea here that they are making money but I cannot imagine how as the roads we have been on just do not seem to have enough customers. I do not know who pays for the roads or who owns them or how they make any money. Maybe no one does. But if you charge too much for your products there will be very few buying them. If you increase prices there will be even fewer buying what you are selling. If you make prices affordable you will make more money. I do have some idea about what it costs to build and maintain roads and I just don't see that costs are being covered in Mexico due to limited use of the toll roads. But I am just voicing an opinion and wonder if there are any facts available that shows costs versus income. I have been across Indiana a number of times and know that traffic exceeds what we see on cuotas in Mexico - so if IN is going broke than how can the roads in Mexico make any money? Does the Gov't subsidize them or are they on their own? Just trying to learn how all of this works. I am not doing a very good job of expressing myself about the questions I have - I don't seem to be able to get my point across.