When driving your car inter-city do you never think ‘if only I could be working, relaxing or sleeping with this time’ like in a train?
There are some city center to nearby city center where rail would be nice, I agree.
Most of the time when I'm going intercity it is by plane.
We don't have any such lanes because only the self-driving car companies have dual mode vehicles.
Nobody's going to market vehicles designed to drive in lanes that don't exist. And building out the lanes and the infrastructure to enter and exit them, probably will boost congestion in the short term.
Self driving car will never match the safety, speed, comfort, and social interactions of a train.