The median family of 4 with private health insurance has a household income of around $115k not counting the gross cost of their employer-provided health care. Remember: being on private insurance puts you in a cohort that:

* Excludes everybody on Medicaid

* Excludes fixed-income seniors on Medicare

* Makes it overwhelmingly likely you have subsidized employer-covered health insurance.

Figure your employer "covers" half the gross cost of your $24k/yr health insurance (they aren't, really: that's money they'd be paying you directly without the distortion of employer-provided health care). Do the take-home pay math. Put them in, like, Ohio, or Iowa, or Colorado; just not SFBA or NYC.

Now move that same family to Manchester, take the wage hit for moving to the UK labor market, and work out the take-home pay. They'll of course pay $0 for the NHS.

Are they better off or worse off?

I'm not valorizing the arrangement, I'm making a point about how political tractable changing it is.