It's a scarce good, which loses most of its value if overused.

The standard Econ solution is to set a price that maximizes throughput. At least some toll roads are attempting to hit that price.

On this note, the "rich people super freeways" model actually does exist and works quite well, when implemented as a totally separate tolled highway that runs parallel to the toll-free one. See: https://en.wikipedia.org/wiki/Ontario_Highway_407