Being in a prime position as both a UK and US citizen, I think I am qualified to explain.
After WWII, the US (and the UK too for that matter) was forced to compete in the Ideological Marketplace. The Right Wing screamed and hollered about Socialism, but Keynesian economics was adopted by the more reasonable of the ruling classes.
Federal Taxes on the highest income earners (like millionaires) was roughly 90%. Taxes on unearned income, i.e. profits (which was how most of the Rich actually made their money) was much higher too. Then the Corporations, eager to show what great citizens they were offered excellent benefits packages to their workers. The Veterans Administration paid for the education of all the soldiers returning from war (the GI bill). Unions were at their peak. Thus a large percentage of the US public shifted into the middle class.
Then came Ronnie in the US and Maggie in the UK. And they weren't having any more of this "coddling" of the populace. They Smashed Unions, cut tax rates on the Wealthy, slashed public services (harder to do in the UK), Corporations cut benefits packages...Keynesian economics was on the way out.
The propaganda machine went into high gear promoting hyper-individualism, and anti-government BS (see Century of the Self, an excellent BBC production). This had all been around to some degree through most of the 20th century, but it kicked into overdrive in the 1980s. And it's been downhill ever since.
The Plutocrats had always been in charge, but, as I implied, the more reasonable wing of the Rich had been ascendant since FDR, and started declining after the assassinations of political leaders in the 1960s. But it still took a couple of decades for the Ultra Right to wrest nearly complete control of the government and to institute a new paradigm.
After Ronnie and Maggie, the fix was in. Any Democratic candidate in the US and any Labour candidate in the UK were forced to cede the ideological ground. Thus the "Third Wayers" like Clinton and Blair were able to get elected by promising progressivism to their base, but in practice continuing the Rightward trends in flattening tax-rates and underfunding public services.
The rest is recent history. Bush the II and the Cabal of so-called "neo-conservatives" (nothing "neo" about them, most of these guys have been high up on the scene since the Nixon years) deliberately ran the economy into the ground and created a Market Crash, just in time for the election of the New Clinton, Barack Obama. Thus the Economic Ideology train runs ever Rightward, even as some ground is begrudgingly ceded on social issues.
The idea of Medicare for all, or some kind of NHS like system was never on the table during the health-care debates. So Barry and his buddies started off the debate from a compromised position: the so-called public option to compete in the market with private insurers.
This was called Socialism/Fascism/Hitlerian/and Stalinism by the Right Wing Screamers, who then organized a campaign of warfare, sending out belligerent activists to disrupt health-care meetings, and Armed Thugs to intimidate Health Care Rallies. The party of NOPE and a few Right Wing Democrats, filibustered everything in the Senate until the Public Option was dead. (Along the way a Right Wing Supreme Court stripped away the remnants of constraints on Corporate election spending).
All that was left was a tentative and mild insurance "reform" package with an Individual Mandate to force people to buy Private For Profit Insurance. This was a windfall for the Insurance Companies looking for more people to fleece. Then the midterms happened. Democrats lost the House, and the Republicans promised to eviscerate any of the good parts of the Insurance Reform bill and make Barry a one term president (to be a lesson to the more Progressive wing of the Democratic Party for ever having the "Audacity to Hope."
The End (of Democracy as we know it)
GB