The numbers aren’t made up. The Federal government publishes these statistics annually, they're widely used by policy analysts, and they're simple to calculate yourself.

The Federal government spends ~$17.5B/year on maintaining and constructing the interstate highway system. Americans drive 852 billion miles/year on it. The cost per Vehicle Mile Traveled (VMT) is 2.1 cents / mile.

If we look at all government spending (Federal, State, Local) on highways, roads, and supporting infrastructure (which includes traffic management systems), that's around $285B/year and 3.28 trillion miles, or 8.7 cents per Vehicle Mile Traveled.

The cost to the government to provide and maintain roads is on the order of several cents per mile traveled per year. Roads are simply much more cost-effective to build and maintain than dedicated public transit infrastructure.