Good points... One possible solution - add people to monitor cars and toss people who are breaking rules. After a while it could be one person to every two cars rather than one to each car... We could call these people 'conductors'... and they'd ride as the expense of the railroads & city government. It'll help until citizens are tired of having our culture and cities in ruins.
In Phoenix, they build a light train from Mesa, through Tempe to North Phoenix. Apparently, it was taken over by the homeless, who do not pay anything, and are just going back and forth in it. It is a great place for them to cool down in Summer or Warm up in Winter.
I would say, in many places around the world, they would be evicted or at lest asked for fare.
Only in America!