I'm still currently hovering around the 80%-90% range. While it seems like there may be some practical issues trying to implement this hypothetical system, It seems like the consensus is that this would be positive in theory. I think a lot of this depends on one's own philosophical/moral values.

If this is specific to the US (it says "US Politics", but I'm not sure), then do you expect the government to actually implement it competently? If so, why?

Otherwise, we have some empirical data on the effects of healthcare programs:

• https://en.wikipedia.org/wiki/RAND_Health_Insurance_Experiment

• https://en.wikipedia.org/wiki/Oregon_Medicaid_health_experiment

My reading of these is that healthcare has some positive effects but some of it is waste. Depending on structure, a public healthcare program might not sufficiently screen out waste. Robin Hanson argues that about 50% of spending is waste in the US right now: https://www.cato-unbound.org/2007/09/10/robin-hanson/cut-medicine-half/, apparently because healthcare's main purpose is signalling care rather than actually improving health.

Labor productivity is increased in healthy people.

Disease and illness are generally more costly to treat when doing so at a later stage, often exponentially so. Providing health care to everyone will decrease barriers that cause unfortunately late presentation of patients.

An early death due to illness means the child-rearing and education investment (paying for schools and associated services) is not recouped (by taxation of working adult), for a net economic loss, which could potentially have been avoided if health care was available. Similarly, early death is an opportunity cost on future labor that did not occur due to early death. This also holds for disabling but not fatal illnesses, down to fairly minor stuff. Everything below the threshold can simply not be covered, and market-based solution can fill the void for those that wish to buy this level of insurance.

Health care expenses under a socialized health care system are, as a goal if not alway in practice, managed by a fact-based rationing system (how much does a given drugs/intervention increase QALY? How much better is the new procedure versus the older one?), which avoids both the cost explosion mentioned in other answers, as well as better allocate ressources than simple cost-based rationing, since human are stupid and ill-informed in the caee of healthcare (I include myself here, I simply do not have time to research everything to the required level). There are thus pseudo-economies of scale in fully integrated, socialized health care systems that cannot be realized at the individual level (e.g. a country level health care system can afford a drug evaluation and price negotiation team, while you can't)

Finally, separating provision of health care from employers will increase currently-artifically-suppressed labor mobility. Solving this will thus curtail some dead weight loss and labor misallocation due to undue employment stickiness. The simplest way to get rid of the employer-health care insurance linkage is probably the provision of health care by some public scheme.

source: trust me bro

@CamillePerrin At individual level one could subscribe to life/health insurance that would ensure optimal healthcare investment according to one's desired spending level while exploiting the economy of scale. Universal healthcare would reduce healthcare efficiency due to free-rider problem and due to a lack of competition between healthcare-organizing systems.

@a2bb individual insurances, assuming you can change contract/coverage level during your life, does not result in optimal outcome because of failure of risk pooling.

Younger and healthier individuals will naturally choose lower coverage (and associated lower price, because the claim rate is lower), while older and more unhealthy individuals has to choose higher coverage (higher price) corresponding to their health care needs. This is a runaway process, since on increasing price, healthier people will segregate away from the higher contract, which will be left with more unhealthy in proportion. and so on. And of course the youngs become old, so they have to change contract away from light coverage eventually.

In the end, the contracts are fully stratified, and do not play the role of insurance anymore: you are paying more or less exactly what people like you consume, at a given year in your life and given health status, not the average over a lifetime and over the population (over people that are "lucky" and people that have accidents, for instance). Whereas the point of the welfare state, in general, is to spread the expenses of childhood, old age, and life accidents, over your income from your most productive years. You can make without, but then the people (and parents!) need to save individually and rationally, for future contingency. I doubt it.

As for competition, healthcare is a sticky product with high information asymmetry (coming back to, people are ill-informed and stupid about health-care), and high regulation level. And empirically, not a lot of country to point to, where one can definitely say, competition made healthcare cheaper.

source: also trust me bro

@CamillePerrin Yes, the essentially infinite resource sink of healthcare is more apparent the older you live, especially if you abused your body. If you worked well, you can afford better healthcare to live longer, insurance or not.

The question is not about welfare state-craft or the benefits of people who can't plan beyond a few months. These people are also more expensive to keep healthy due to their unhealthy habits that result from such shortsightedness.

Your answer doesn't address the fact that competition reduces prices due to removal of corrupt or otherwise inefficient companies from the market.

Healthcare is an infinite resource sink even for a single person, so only the worthy should receive it, according to their feats (money) and desires.

Preventative health care has a lot of social benefits, and the more people can access it, the better.