> As we all know, market prices are an efficient mechanism to allocate scarce resources. People have a curious blindspot about this when it comes to roads.
It's not a blind spot. It's a characteristic of services with a high fixed cost and trivial variable cost.
To ask if we should price roads is to ask if the price needed to deter usage enough to relieve congestion without expanding the road would generate less revenue than it would take to expand the road. But this is basically never the case because most of the expansion cost is one-time (e.g. buying the land) whereas the congestion charge would have to be collected forever to continue deterring usage.
The strongest case for not expanding the road is if there is a more efficient way to relieve congestion, e.g. by relaxing zoning restrictions to allow higher density housing and reduce travel distances.
But if people value using the road at more than the cost of expanding it, and there are no higher efficiency alternatives, that implies the road should be expanded. And once it has been and there is no congestion even at zero unit price, there is no benefit in charging a unit price to deter congestion that isn't there anyway, and a detriment in deterring use of a public resource for which the same fixed cost has to be paid whether you use it or not.
Charging road tolls is also especially inefficient because the collections process has a high administrative overhead and a high privacy cost. Every dollar spent collecting tolls -- toll tags, gantries, billing, maintenance, customer service -- is a deadweight economic loss not incurred by any alternative that doesn't require them. The privacy cost is the same.