There is almost always an expectation by those with no insurance
that someone will take care of them. At the individual level, they do receive care.
But at a societal level there is still the expectation that if you can afford it,
you should be paying your fair share.
This is what the Obamacare "tax" is all about.
It's your choice to refuse to buy insurance, but as a member of society
you should still participate in some way ... $ if you can afford it.
(The IRS is there to help you make your decisions
)
I'm not sure if it fits the precise definition, but "moral imperative" comes to mind,
just as society has an imperative to take care of those who can't care for themselves.