At a muni level, which is where a lot of public transit is done, you are hardly empowered to fix social problems a thousand miles away, so your options are limited. You try to turn away transients, or you don't. SF is in the latter camp, of course.
You describe me as espousing the mentality that blocks public transit. But really, I'm just observing, it is a matter of fact that interstate rail is a source of crime in our town. You can show a crime map of our town, and there is literally a hotspot around the rail line. But I'm still pro-transit, pro-rail, the whole shebang.
If anything, I feel like trying to wave arms, point fingers, & distract from this indisputable fact is sweeping things under the rug. Better we acknowledge it, and include what we're going to do about it in our pitch & plan.