Governments sometimes demolish highways though. And a lot of the time, the marginal utility of adding another lane to a road is lower than the utility of using

Governments sometimes demolish highways though. And a lot of the time, the marginal utility of adding another lane to a road is lower than the utility of using that space and public money somewhere else. If we scale a car-centric city to a million inhabitants we often end up with a majority of urban space devoted to roads and parking lots, which cost public money, instead of commercial and residential buildings which generate opportunities for the inhabitants and money for the municipality. Another problem of car-centric infrastructure is that it doesn't scale as well as public transport - a single bus can, potentially, take 50 or more cars off the road.