Cultural factors like ethics that entail helping people and educating everyone that anyone could end up in a vulnerable situation and then dedicating resources to make sure everyone has a safety net in case they lose their job, have a mental illness, addiction or something else unexpected?
Then just look at the distribution in the USA: Among the states with most homelessness per capita are: District of Columbia, New York, Oregon, Washington State, Alaska. Yes, also Californa, but California has most of everything, including housed people.
Aside from D.C. and New York, these are all states within the ninth circuit court’s jurisdiction, and therefore are bound to the Martin v. Boise ruling, which allows public camping if there is not adequate shelter space available. If one part of the country allows that while the rest doesn’t, you’d expect that the homeless population will migrate over time to the more permissive area, which seems to be borne out in the growth of the homeless population on the West Coast since the ruling went into effect. Of course, we also mint plenty of new homeless ourselves with our astronomical housing costs, but I see a lot of people with out-of-state plates on the RVs they live in here in Oregon.