Where can the USA look for similarities? Singapore is one city state, as is Hong Kong. Australia's cities are 600 miles apart. The EU has a language issue moving from city to city, despite London to Paris being 1/10th as far than SF is to NYC. The USA is pretty unique here.
The one similar country is China. The GDP per capita by Chinese prefecture makes the US look positively egalitarian: https://en.wikipedia.org/wiki/List_of_prefecture-level_citie...
China solves their issues by essentially banning movement between areas. The US could never solve their issues that way, for a variety of reasons.
So I'm not sure what the solution is to micro level high homelessness, but macro level low homelessness.