It seems to me that libraries would prefer not to deal with this stuff either. Much like how police are often dealing with things that aren't really police matters, the reason for this state is that we as a society have decided to largely abandon people in dire need.
Libraries (and police, and other services) are left to deal with this problem by default, because we as a society don't value finding solutions to the problem enough to bother to do that.
Is it possible that rather than abandoning people in dire need, we're now actually trying hard to help those in need instead of criminalizing bad luck and pretending they don't exist, but that that is exceedingly hard to do well?
There is certainly a greater interest in finding real solutions than there has been for decades, yes, and there are absolutely certain groups that are trying hard. I think the trendlines are heading the right direction here.
But, as a society in general, I think we're not actually trying hard yet. We're still largely debating whether or not we should be.
These people can't be helped. Meanwhile, you are harming functioning healthy people and destroying any public space at great cost to everyone paying the bill. We are all sick of it.
No, I don't think they can be helped; additionally, I don't accept that functioning productive people have to sacrifice their comfort or well being to accommodate these people's problems.
I don't think they can be helped, but certainly letting them mill about in public libraries accomplishes what exactly? Yes, I write them off because I am a realist, not a utopian, and I write them off because on balance they cause so many problems for normal people.
It is not worth destroying nice places, cities, libraries, streets for pie in the sky morality that presumes mental illness to this degree or drug abuse can be overcome, or that it is worth all of the mess, harassment, violence, filth, and degradation that we all see everywhere waiting around for this supposed solution that never comes. It's not working.
Libraries (and police, and other services) are left to deal with this problem by default, because we as a society don't value finding solutions to the problem enough to bother to do that.