It’s a question of economy of scale. The amount of road vehicle that has been built over the last 150 years vastly supersedes the amount of train over an even l

It’s a question of economy of scale. The amount of road vehicle that has been built over the last 150 years vastly supersedes the amount of train over an even longer period. More train, means better train. Hopefully advances in computer aided design will allow some narrowing of that gap. EDIT: There is also an inherent feature in trains that greatly reduces the rate of progress. With toad vehicles there is very good decoupling between the track and the vehicle, from a design pov. With trains the chassis design is more coupled to the track design. And since you can’t really upgrade track easily, on both train and road, there are more constraints in new train design.