It's really sad and I see why people blame the police for arresting these folks who are already struggling. But, to be fair, the police aren't acting independently; they are told exactly what to do and who to arrest by people much higher up.
I've seen it here with out Trax train system, homeless people getting harassed by the patrolmen who come along to see if you really bought a ticket or not. And it really is heartbreaking, I just want to say "let me pay for them" but it isn't allowed.
Obviously when this kind of thing is out of control, there's a system problem not just a people problem. I don't know why we can't make mass transit easier for people who are already having difficulties most of us can't even comprehend.