It's somehow more important to give someone the right to sleep on a street corner at noon (something I witnessed just today, in an area where there usually aren't many/any homeless people), than it is to help get them on their feet, plus allow the rest of us to feel safe and not have to deal with garbage, human shit, and needles all over.
[0] That's the other thing, though: I doubt we have enough shelter beds to cover all the homeless people here. Yet another thing that needs to be fixed. I hear NYC is able to house around 95% of their homeless, and we're a much smaller city.
On top of this, if you are addicted to drugs, you might be unable to safely detox. Cutting cold turkey in a shelter sounds like a nightmare and I wouldn’t be surprised if a bum would prefer remaining addicted on the street than vomiting/sweating/sick in a shelter full of strangers where you’re too vulnerable to fight back if anything goes wrong.
More realistically, I’ve known folks who refuse to go to shelters because the shelters demand them to give up their pets, aka their family and what’s getting them through the traumatizing experience of homelessness. Or they’re told to give up their possessions for being too bulky or much, even though there’s no guarantee they might not need all that gear back if they’re later kicked out or age out or housing falls through.
Literally incarcerating people just for being too poor to afford decent housing is also ethically abhorrent, of course, but it's also not the most effective way to reduce the problems that are bothering you.