Regardless, unless they work in Pontiac, B'ham, Detroit's New Center area, Royal Oak or Ann Arbor, they will still need transport from the train station to wherever it is they work.
So following your reasoning, everyone will move to a town where Amtrak has a station and work in another town where Amtrak has a station. Further, they will find homes and jobs within walking distance of said station.
Rentals and housing costs in those locations would really skyrocket, wouldn't they? And then wouldn't it be just as economical to drive to where you work?