The author compares the safety and throughput of self-driving cars to trains, where they should have compared against regular cars. The problem with trains is the infrastructure isn&#x27;t there and will not happen because it&#x27;s impractical in an already developed metro area, and even if it magically happened the longer travel time would cause most people to still opt for cars. Self-driving cars will reuse the infrastructure that is   already there and use it much more efficiently, so they are definitely a significant improvement.