It's still cheap compared to that.
If you want an emergency services vehicles to get to your house you need a road anyway.
If you want buses and coaches to function, you need roads.
If you want to transport a bootload of stuff more than three times a year you're financially better off paying for a car than renting.
If yor kids have school anywhere that isn't walking/cycling distance from your house, then you need a car, or two.
If you have a job, and don't want to be beholden to a very local employer, you likely need a car. Except if you live close to a train station and your job is close to another one. And except in the last five years, when some jobs can now be remote.
If you want to go anywhere that a train doesn't go, you need a car, probably. Which is everywhere outside of extremely high density urban areas that can afford an underground rail system.
You need any of those things to be true for a road to be needed. You likely need a car for all but the first two. Cars and roads are valuable. I don't see how that's debatable.
Trains are now location-specific optimisations where we know we have hotspots of usefulness, where it's worth laying track and having massive investment as enough people will use that route.
Just as a circuit-switched phone call is a better connection, but packet-switched is better overall, and cheaper, so are trains and cars.