Note that I'm obviously not claiming that higher taxes necessarily cause worse problems, but a negative correlation like this is strong evidence against any claims for a positive causation of (higher taxes -> less homelessness and drug addiction).
There have been many articles and studies written elsewhere on drug addiction and homelessness, so I won't repeat the details -- but my understanding is that the general consensus is that solving this requires policy change more so than funding change (but obviously both are necessary for the best results).
More taxes does not automatically mean they go into fixing the core of the problem nor does it mean they'd fund the mental health program enough to address most of the problems.
Mental health is not a single cause of the homelessness problem that is "infecting" the west coast right now. For an example, medical bills could easily and have bankrupted people without actual mental problems. So, how would funding mental health facilities going to help these people have a home?
Mental health support will be provided when it is actually a priority. It clearly isn't for most of the state.
Seattle is an unfortunate perfect storm of issues due to rapid growth.
For comparison, ~0.90% in SF, and ~1.45% in LA.
The homeless crisis has nothing to do with cost of living (example, look at other extremely expensive cities around the world).
It’s because we took all of the mentally ill and drug addicted out of psychiatric asylums and threw them on the streets.
The opioid epidemic is a US-only problem, so looking at other world cities won't tell you much beyond "Yeah, Purdue pharma shouldn't have convinced doctors to get millions of people addicted to opioids."
The reason why Seattle attracts permanent nomads and drug addicts is simple. The city simply does not enforce laws and lets them do whatever they want. Even worse, it selectively enforces laws - if you are a law-abiding resident, you will be subject to the law in situations like parking enforcement, littering, environmental laws, and so on. For example, a car cannot be parked in a public parking spot for more than 72 hours and if you or I were to leave a car parked for that long, we'd have a ticket. Littering anywhere carries serious fines. And homeowners have to deal with a draconian set of codes that govern their ability to use property they own and pay property taxes on. But if you are homeless, you can get away with parking RVs permanently in public spots (taking away street parking from actual residents), you can trash up public and private lands, and you can leave needles/feces/trash in wetlands/greenbelts/wherever without consequence. Here's an example of differential enforcement of laws in Seattle, where a construction worker living in an RV was fined while other nearby RVs for "homeless" were not fined: https://mynorthwest.com/1046331/construction-worker-rv-ticke...
No one has a right to live wherever they want, at whatever price point they want, doing whatever job they want (or not working at all), and so on. People have to show personal responsibility for their choices (for example not trying that first hit of heroin), live within their means (instead of expecting to live in a highly-desirable and expensive location), and obey the laws (in support of the social contract). Taxing Seattle or Washington residents to support the lifestyles of those who don't do these things is punishing residents who play by the rules for those who don't. Instead, the city government needs to enforce the law strictly, and create conditions/consequences that disincentivize people from abusing the city's goodwill.
1. I find the use of the word 'dehumanize' to be unnecessary and hyperbolic. This is commonly used to shut down opinions that concern some cohort of people. It is not precise or helpful, and is an appeal to emotion. I didn't state anywhere that homeless people aren't human. I did state that people need to live within their means, obey the laws, respect public spaces, and not be coddled by lax/unequal enforcement of laws. That's not dehumanizing, it is common sense. The proliferation of tents, trash, drug abuse, and property crime in Seattle is wholly unacceptable and the result of short-sighted governance. Pushing back on bad policy to protect my interests is not dehumanizing someone else - if anything, those who trash this otherwise beautiful city are dehumanizing its residents.
2. I addressed this specific survey that you linked to in my comment. The point in time survey is not rigorous. It does not verify the identities or past backgrounds of any respondents. It relies solely on their goodwill to answer truthfully. The homeless who respond have an incentive to lie about where they are from, because making it look like they are long-time local residents is more likely to result in public support for them. The volunteers who conduct these surveys are all either participants in the homeless industrial complex (see https://www.city-journal.org/seattle-homelessness) or are activists who ideologically support the homeless. These volunteers coach homeless to respond in ways that are favorable to the homeless themselves, to these organizations that constitute the homeless-industrial complex, and the ideologies of those same activists. The only data that would be acceptable regarding the origins of the homeless is strongly-verified/provable identification of respondents. Anything short of that is not rigorous and acceptable, and therefore it is not a myth to claim that the majority of homeless people in Seattle are transients from elsewhere.
This is both a nationwide and statewide problem. But the lack of state income tax makes it harder for Washington to better fund mental health facilities in the state. The state prides itself on its progressivism and compassion, but it's 23rd in the nation for per capita mental health funding.