There are a great many people who benefit from roads indirectly via the services and commerce they provide.

Not all market transaction systems are effective at capturing sufficient amounts of consumer surplus to make provision of services possible.

As another example: many private (and public) transit systems were funded and financed by retail and real estate interests. By covering the fixed capital and much of the operating expenses of bus, trolley, and rail lines, they increased demand for their products and services. You see this today, but it comes in the form of providing "free parking" for retail establishments (you think those acres of parking outside your local mall or WalMart don't cost anything?).

Markets have failures too, my friend.