You are attacking a straw man at this point.
No. I'm not. You stated that programs which provide housing don't work. You're not basing that on research or evidence, but on unverifiable anecdotes.
My argument is that you can't just treat all homelessness as the same because there are different reasons for people being homeless.
No one is saying that there is one, and only one, solution. That said, research does show significant benefits to the Housing First model (which, by the way, is a specific set of policies, and certainly isn't the only option out there).
Of the 25,000 people that Houston housed, the vast majority were not in tent cities.
That paper is from
2009. That's from BEFORE Houston started its "housing first"-based policy.
Back in the real world, Houston has worked on moving people out of encampments for several years now. They were delayed a bit due to litigation, but got approval from the courts in 2017.
City officials argue the tent cities and encampments, primarily under freeway overpasses, are hazardous to public health and safety
www.houstonpublicmedia.org
We have doubled the number of housing first units nationwide and have not reduced the number of overall homelessness.
https://www.huduser.gov/portal/publications/homeless/hsgfirst.html
That article is from
2007. Why are you citing papers that are over a decade old?
Why are you citing it at all? It actually
supports the Housing First policy for homeless people dealing with substance abuse, while acknowledging that there are challenges (e.g. merely providing housing doesn't fix all of a person's issues; continued drug use while housed etc).
As to "more housing:" There was a housing bubble in 2007, building lots of expensive units -- not
affordable homes. After the bubble popped (i.e. after the paper was written), construction halted, leaving the US with a deficit of new housing.
https://www.huduser.gov/portal/publications/homeless/hsgfirst.html
In fact, we actually see an increase in substance abuse rates:
https://doi.org/10.1080/15504263.2017.1319586
OK, again? Are you reading your own links? That study names multiple benefits for a housing first approach for homeless individuals with substance abuse issues.
https://doi.org/10.1080/15504263.2017.1319586
If you just put people in housing without requiring substance abuse treatment and mental health treatment and compliance with it, then you aren't fixing anything.
Talk about a straw man! Housing First includes access to that type of help. The key differentiator here is that HF doesn't put any strings on housing.
There are basically two things that are driving homelessness in America:
1. A lack of affordable housing in some areas.
2. An an opioid and meth epidemic.
https://www.huduser.gov/portal/publications/homeless/hsgfirst.htm
What the... Why are you pointing to the same link, from a document written
before the opioid crisis?

Anyway:
1) Correct.
2) Nope.
Opioids and amphetamines were mostly a problem in rural and suburban areas. That isn't where we are seeing the major increases in homelessness.
Further, the claims about an opioid "epidemic" are... complex. What is undeniable is that the number of
overdose deaths has increased significantly, and roughly 20% of that is specifically fentanyl.
What is less clear is changes to the the
number of people using drugs over time. For example, the popularity of different drugs can rise or fall over time -- e.g. cocaine use has fallen significantly since the 90s, while opiate use rose. It may not seem this way, because the media is always reporting the bad news -- "drug use up! Scary new killer drug!" but that does seem to be the reality.
I.e. claiming that "more people are abusing drugs, and that's causing more homelessness" does not fly.
And again...
What are your solutions? What is the evidence for your solutions?