because its voluntary

That's your problem right there. Many of these people are too sick from mental illness or addiction or both to seek out and stick with help, and many simply prefer their psychosis or illegal high to real treatment.

Society is a social contract. We all agree to behave responsibly and not attack or threaten each other, because that makes things better for all of us. Yet many homeless people opt out of that contract. They behave in ways that threaten and make the rest of us feel less safe, less peaceful. And that's leaving aside the actual attacks.

Don't get me wrong, I'm not opposed to homelessness per se. I'm opposed to bums. People who don't work and won't work and don't give a shit about being good social actors. You can live in your car and not be a bad social actor. But when you're living in filth and aggressively panhandling and acting like a madman because of psychosis or drugs or both, you've opted out of the social contract. You've opted to harm the rest of us.

Your argument appears to be that that kind of behavior is what is intended to be protected by civil liberties. As though freedom of speech and assembly are furthered by that kind of behavior. I get it, restrictions are repugnant, but when the fundamental premise of social decency is contravened, when common sense is dumped in favor of "it's ok to openly shit on BART," we've gone too far.