Then how did the other 31 of the 32 developed nations manage to pass it? Some democracies, some not. Some with strong unions, some not. Some with historically strong economic sectors, some not.

Clearly there’s a way it happens. Why can’t we find the path?

Three reasons. First, and most important, because they all did it when their healthcare sectors were small. I asked AI to put together a list of all the OECD countries, the year they established their system, and the relative size of the health care sector at the time. Generally, they all made the change when the health care sector was 5% or smaller of the national economy. That allowed the state to pay for the system using the monopsony power to keep provider compensation low enough to make this politically possible. None were anywhere close to the size of the U.S. system.

Second, nearly all of those countries are parliamentary systems, which simply present fewer "veto" points for passing significant legislation. Whoever wins the House of Commons (or analogous lower house) gets to form the government.

Third, most of those countries adopted their programs a while ago, under structural characteristics of the political process very different from those that exist in the U.S. today. They lacked the characteristics that make it possible for special interests (which unions, doctors, and retirees are - as well as the evil insurance companies and nasty pharmaceutical firms) to effectively express the elections intensity of their political preferences. A good chunk of them were adopted prior to the big role of television in elections, of course. But all of those countries have small electoral districts and strict rules on campaigns that simply don't exist in the U.S. national system.

Country		Universal Health Care Establishment Year	Health Care Sector (% of GDP in/around Establishment Year)
Costa Rica	1941						~2.5% (1940s estimate)
France		1945 (Securité Sociale)				~3.0% (1950 estimate)
Chile		1952 (FONASA predecessor)			~3.0% (1950s estimate)
Japan		1961						~3.0% (1961)
Germany		1883 (Bismarck worker system) / Universal 2009	~3.0% (early 20th c.) / ~10.5% (2009)
Norway		1912 (Subsidized) / 1956 (Comprehensive)	~3.2% (1960)
Belgium		1945 (Compulsory social insurance)		~3.5% (1950s estimate)
Iceland		1946						~3.5% (1950s estimate)
United Kingdom	1948 (National Health Service)			~3.8% (1948)
Luxembourg	1901 / Universal coverage formalized		~4.0% (1970s)
Korea		1989						~4.0% (1989)
Latvia		1991						~4.0% (1991)
New Zealand	1938 (Social Security Act)			~4.2% (1950 data)
Lithuania	1992						~4.2% (1992)
Sweden		1955 (Compulsory national insurance)		~4.5% (1960)
Austria		1967						~4.8% (1970)
Greece		1983 (National Health System)			~4.8% (1983)
Portugal	1979 (Constitution/NHS)				~5.0% (1979)
Czech Republic	1920 / 1992 (Reformed)				~5.0% (1990s)
Estonia		1992						~5.0% (1992)
Slovak Republic	1992						~5.0% (1992)
Colombia	1993 (Law 100)					~5.0% (1993)
Poland		1999						~5.0% (1999)
Mexico		Near-universal target via 2003 Seguro Popular	~5.0% (2003)
Australia	1975 (Medibank) / 1984 (Medicare)		~5.5% - 6.0% (1975/1980s)
Finland		1972 (Primary Health Care Act)			~5.5% (1972)
Spain		1986 (General Health Act)			~5.5% (1986)
Hungary		1990 (Constitutional universal access)		~5.5% (1990)
Türkiye		2003 (Health Transformation Program)		~5.5% (2003)
Ireland		1970 (Health Act)				~5.6% (1970)
Canada		1961-1971 (Phased via Hospital/Medical Acts)	~5.7% (1961) / ~7.2% (1971)
Italy		1978 (Servizio Sanitario Nazionale)		~5.8% (1978)
Denmark		1973						~6.3% (1973)
Slovenia	1992						~6.5% (1992)
Israel		1995 (National Health Insurance Law)		~7.5% (1995)
Netherlands	1941 (Order) / 2006 (Major reform)		~8.9% (2006)
Switzerland	1994 (LAMal passed, eff. 1996)			~9.0% (1996)