The problem with trains is that once you get off the train, you're stuck back on foot and in the US, that's a major pain in the ass. Either it's an uncomfortable rental car that you struggle to find the right buttons and shit on or shoddy and slow public transportation that might not take you anywhere close to where you actually need to go.

Now the obvious solution is to simply combine the ability of the car to drive anywhere there is a road with the ability to ride on the tracks of a train. Imagine a platform sitting on railroad tracks that you could drive your car onto that had some sort of dyno for the wheels of your car to provide power to the wheels of the platform that contact the rails. If you locked the car in place with clamps or straps, the car's engine could continue to provide the power needed to propel the car on the tracks.

Now there are some obvious difficulties, but I think they can be overcome with technology. This is what autopilot technology was designed to work for, not roads. A nice clean and clear track with only one possibility for something to be in front of you and one in back. Sensors could easily locate other cars and compensate, additionally you could even give control over all the cars connected to the train to a computer that would leave adequate distance between cars. Additionally, the cars wouldn't have to stop since a simple loop of track with a computer controlled switch for exits could allow the cars that are going by to continue on while diverting exiting traffic to the loop. The computer could also control when newly loaded platforms entered using the same loop.

Electric cars could also charge up while on the tracks if an electrified third rail was added so you could reduce the size of batteries in cars as any time you needed to go a fair distance you could actually charge up while doing so.

Any reason something like this isn't being implemented?