[1] https://www.bostonglobe.com/metro/2016/02/28/mbta-shrinks-it...
[1] https://www.bostonglobe.com/metro/2016/02/28/mbta-shrinks-it...
FWIW TfL in London has to break even across all modes (operationally, at least) by 2018.
You'll notice there is an exceptionally high correlation between operational returns and city density.
So do highways — they're all investments which make things better for private citizens and businesses. You have to look at the total economic impact — i.e. not having public transit would entail either trillion-dollar freeway construction projects, the economic hit of massive traffic jams, or some combination of the two.
Perhaps public transit fulfills a different role in a country where car ownership is aspirational and currently at < 10% vs a country where car ownership is the norm and >90%