Aside: having a little first and close secondhand experience of homelessness and hostel provision, it seems to me that many people think drugs and mental health issues are the key causes. This is untrue. I'd say there is a "core problem" of those issues, which would be very difficult to solve, but it is a minority. I also wonder how much those problems are secondary symptoms rather than causes. Live on the street long enough and you'll be wanting an escape, for example.
In London my experience was that a large number (majority?) sleeping on the streets were there because of benefit sanctions, i.e. they simply could not afford to live in a house as the government had removed their social welfare. Some people were waiting to be housed etc.
It only takes a moment's thought to notice (a) the difference in prevalence of homelessness between countries, (b) the difference in prevalence over short time periods within the same country, to see that it is government policy that large determines the extent of homelessness. When governments don't provide good welfare nets, social housing, and social services to help people, homelessness is higher.
In London my experience was that a large number (majority?) sleeping on the streets were there because of benefit sanctions, i.e. they simply could not afford to live in a house as the government had removed their social welfare. Some people were waiting to be housed etc.
It only takes a moment's thought to notice (a) the difference in prevalence of homelessness between countries, (b) the difference in prevalence over short time periods within the same country, to see that it is government policy that large determines the extent of homelessness. When governments don't provide good welfare nets, social housing, and social services to help people, homelessness is higher.