The airline industry embraced point-to-point routing in part because it reduces their costs on inelastic infrastructure on the ground, and allows them to tailor their schedule around demand at the two endpoints rather than on maintaining a network. They pay-as-they-use for airport gates and lessened their spending on hubs.

Fixed-guideway transport infrastructure (trains, busways) and dedicated structures (tunnels, bridges, airports, etc) come with high capex that must be borne by the builder. One advantage of road-based transport over rail-based transport is that the road is already there and will (often) already be built and expanded by the government just to allow private vehicles to come and go -- it's multipurpose -- while any other mode of transport requires this infrastructure to be purpose-built and maintained for the transport mode itself. That costs.