Mexico toll road discussion?

I do understand some of the toll structure but my question came up when I saw the story about the bankrupt toll road in Indiana. The story said the reason is that there are fewer vehicles using the road therefore less income. My thinking is if they charge too much then people won't or can't use the roads. We find the tolls in Mexico to be very high but we pay them anyway if there is no reasonable alternative. In some cases the cuota runs very near the libre and the libre can be seen. We still see more traffic on the libre than the cuota and assume this is because the high tolls. My reasoning is that if they lowered the tolls they would increase traffic and thereby increase income. Based on our observation of traffic on cuotas we can't imagine how some of them can have much income at all. Though some are heavily traveled because they are the only usable route there are others where traffic is very light because alternative routes are available. So in there somewhere is what I am trying to get at - are high tolls keeping people from using the roads - would lower tolls increase revenues to make roads profitable - does the bankrupt road in Indiana have anything to do with Mexico (meaning do high rates lower use and lead to bankruptcy?)?? We assume the average Mexican cannot afford to use the toll roads - or they do not think the cost is worth it to them.