Correction, trains specifically. Subways and light rail are immensely higher ROI (as in, benefit vs cost) within a city since it effectively forces people close

Correction, trains specifically. Subways and light rail are immensely higher ROI (as in, benefit vs cost) within a city since it effectively forces people close together, while a 6-lane-on-each-side highway isn't economically feasible for all of the high-traffic areas.