Coefficient Giving's @mattsclancy reveals why America's biggest transportation breakthrough might not be high-speed rail, but cutting massive infrastructure costs: "If we go big on transportation, it’s not a given that it will look like we should all have high-speed rail across the country. It might be more about autonomous vehicles. It might be about congestion pricing." "Probably a big part of it will be about why does it cost so much more to build the same kind of transit infrastructure in…