Your premise doesn't align with the
facts.
Poverty and homelessness are near all-time lows in the US right now, comparable to Canada. You wouldn't know that by looking at the streets of San Francisco (or Los Angeles for that matter).
At a national level homelessness has declined dramatically since 2000. While San Francisco's problem has only kept getting worse. The US as a whole isn't seeing the homelessness problems that San Francisco is.
While San Francisco was doing nothing, the US implemented the Housing First program under the Bush Administration. That policy was continued and amplified by the Obama Administration, to extraordinary results: homelessness declined through the great recession, rather than skyrocketing as would have been predicted (especially coming out of a housing bust).
Unsheltered homelessness is down 20% since 2007. Total homelessness is down by 15% since 2007.
https://www.hud.gov/sites/dfiles/Main/images/hudno.18-147.jp...
2010 > Obama builds on Bush success to help the homeless
https://www.csmonitor.com/Commentary/the-monitors-view/2010/...
2013 > The federal Department of Housing and Urban Development reported that the number of the chronically homeless declined by 30% between 2005 and 2007. You might have expected the numbers to spike again when the financial crisis hit but no. Since 2007, the number of chronic homeless has dropped another 19%.
https://www.cnn.com/2013/04/29/opinion/frum-less-homelessnes...
2008 > On a cold January morning in 2001, Mel Martinez, who was then the new secretary of housing and urban development, was headed to his office in his limo when he saw some homeless people huddled on the vents of the steam tunnels that heat federal buildings. "Somebody ought to do something for them," Martinez said he told himself. "And it dawned on me at that moment that it was me." So began the Bush administration's radical, liberal — and successful — national campaign against chronic homelessness.
https://www.mcclatchydc.com/news/politics-government/article...
2013 > The Astonishing Decline of Homelessness in America
https://www.theatlantic.com/business/archive/2013/08/the-ast...