In a market-republic society, initiatives such as private automobile technology create a formidable alliance of interests which mass behind the concept of "car > rail":
- Automobile manufacturers: they can sell more cars.
- Fuel industry: Petroleum exploration, extraction, refining, transportation, distribution, and retail sales.
- Independent automobile dealers and repair facilities: sales & services.
- Auto suppliers: Support industry based around the manufacturing and repair.
- Construction companies: Road and highway construction and maintenance.
- Travel and tourism: Auto travel and auto-based tourism ("road trip", car rentals associated with other transport, etc.) emerge.
- Real estate. Automobiles promote suburban sprawl real estate and development. This brings in construction, development, finance, brokers, title insurance, and more.
- Media: Auto advertising becomes a major component of print, broadcast, and cable media.
- Training and instruction: Drivers' training and related services.
- Licencing: Government infrastructure around vehicle and driver certification and registration.
- Sport: Auto racing creates its own fandom and dynamics.
- Popular culture: Various fandoms, tribes, and allegiances based around specific brands, concepts, and activities.
It would be difficult to intentionally devise a more effective self-sustaining, self-perpetuating market-political consortium. I don't believe that the automobile-support-industrial-complex was intentionally conceived --- it is an emergent concept. But once emerged it's phenomenally resilient.
We've seen a few related sectors. The military-industrial complex identified by Eisenhower is one. I'd argue that the healthcare-industrial complex is another. The food and ag sector likely a third.