A great deal of spending in the US suffers the problem of direct versus some form of market disintermediation. So, instead of just building houses for people, we funnel it through myriad private or semi-private bureaucracies and suffer their corruption and graft.
That appears to be happening in Finland as well. The article says that state funding is funneled through "NGOs such as the Y-Foundation" who are responsible for actually getting the housing.
Yes, it’s not a binary situation. But Finland also directly took over several private/NGO shelters and converted them to apartment blocks. In the US, this would be considered verboten in most major cities because of the challenge it poses to everyone involved in real estate speculation and development.
The US citizen sees a fraction of their tax dollar ever actually reach the ground. The rest gets caught up in people's pockets on the way down. We would need to adjust for this but it's unclear how to create a heuristic.
I don't, because I don't know how to calculate it. Like I said, we need a heuristic but I don't know how to go about it. But it's an important qualifier when we're trying to isolate this problem to just the economics of solving homelessness.