Some roads do collect tolls. Again, I don't know how to look it up, but I don't think they have government help. They're in the minority, but they show that having roads is socially optimal. Similarly, if there are high-speed trains that operate without government help, we know that it's good to have high-speed trains, and while it may be that government encouragement is resulting in too many of them being built, we should still build some.