Mass transit requires density. Density of housing and density of employment.
Density requires a level of competence in governance that many US cities appear to lack.
And density requires a populace willing to suffer the indignities of such density too ... unless you were proposing that government should impose it regardless ... or that government can wave away those indignities.
Just noting that if city governments were more competent, mass transit would not be an issue as cities would be a more desirable place to live and work as compared to the burbs.
Whenever I see a new mass transit proposal put out by a nearby city, it seems that the major underlying reason is to have a public works project to steer money to vested interests rather than to provide useful transit.