If you look at the US metro areas with the highest productivity (defined in this article as GDP/capita) [1], they are definitely not the ones with the best or even extant transit.
[1] https://www.statista.com/statistics/248112/per-capita-us-rea...
The average is about 25 minutes and it goes up by only a few minutes in especially congested places. (If a 5 minute traffic jam is existentially distressing, wait till you see what waiting for the train is like).
https://www.npr.org/2018/09/20/650061560/stuck-in-traffic-yo...
San Jose and Sunnyvale have the cal train, linking a 50 mile long area into about an hours worth of travel. Bridgeport and Stamford have the metro north train, enabling commutes of 40 miles for tons of people to New York.
Consider what would happen to the South Bay if the Cal Train closed, or to Connecticut if the Metro North shut down. Way fewer workers would be able to to live their, and the populations would shift.