This strikes me as the main problem with the mindset around HSR. Consider e.g., Madison, Wisconsin.

Milwaukee would have a much more vibrant and dynamic ecosystem if undergrads/PhD students/professors could get to/from meetings with investors in MLK/CHI and be back for afternoon classes. Or continue internships/meetings during the school year.

There are enormous inefficiencies (and corresponding brain drain) caused by the fact that the region's center of innovation is 1+ hours by car away from the region's center of finance.

An MLK <-> CHI <-> Madison rail line would change the dynamics of the entire state's economy. Simply counting cars on the roads between those cities in the present ignores how HSR changes the entire dynamic in a very qualitative way.