Another way of looking at it, building transit doesn't get anybody to work faster, but it does allow you to scale population density, which in turn allows you t

Another way of looking at it, building transit doesn't get anybody to work faster, but it does allow you to scale population density, which in turn allows you to build more housing for a region that may be in a housing crunch. If you can imagine that one day the world woke up, and some god replaced every building in LA with a skyscraper and every parking lot or driveway with a multi-story parking garage, you could use Marchetti's constant to predict what happens next: People move closer to work to reduce their commute, then the roads in the inner city get more and more congested, and the effective size of the city shrinks to fit the "1 hour commute" rule as it's now impossible to live in what are currently middle and outer neighborhoods, as their commutes would far exceed 1 hour. Adding more transit allows us to grow the effective size of the city even if every building in the city is a skyscraper. On a smaller scale, this is basically Manhattan, after all.