Simple geometry argues that you can fit more people on dedicated train cars than a fleet of independent vehicles. You don't get 100% of the benefit of stop-free

Simple geometry argues that you can fit more people on dedicated train cars than a fleet of independent vehicles. You don't get 100% of the benefit of stop-free transit in the real world because there will be pedestrians - you need a dedicated right of way. The argument for independent vehicles was made with rail PRT too, and it only ever reached a niche campus-and-airport market. What you get from autonomous vehicles is improved flexibility, and that improves all transit modes while only slightly changing the dynamics that make rail vs. bus vs. car interesting.