Universal healthcare is only possible because of private insurance. Regarding your question, a good place to start is knowing the basics of health insurance, which is
not healthcare, but healthcare finance. Here’s a very brief primer on the five basic forms of health insurance:
- Socialist: The government owns the hospitals and directly employs the doctors. Britain’s NHS is the best known example. In the United States, VA healthcare works on this model.
- Single-payer: Doctors and hospitals are mostly private entities, but are paid exclusively by the government. Canada is single-payer, with each province acting as the sole source of payment to doctors and hospitals. In the US, Medicaid and traditional Medicare are single-payer.
- Multi-payer: Same as single-payer, but doctors and hospitals are paid by multiple sources: the government, regulated sickness funds, regulated insurers, etc. There’s a continuum in multi-payer systems, from those that are almost single payer (France) to those where other payers play larger roles (Germany, Belgium, the Netherlands, etc.). This is the most common form of universal healthcare, and its advantage over single-payer is that it offers a little more flexibility in coverage. In the US, Medicare Advantage is basically multi-payer.
- Subsidized private: People are required to be covered by private insurance, but the government provides subsidies to make coverage affordable. Switzerland uses this system. In the US, this is the Obamacare model.
- Private: In the rich world, this is used only in the United States. Employer healthcare in America is essentially entirely private, although government is involved indirectly via the tax code, which allows employees to receive health coverage free of taxes.
All of these except the last are universal healthcare systems. They differ only in how they deliver services and pay for them, and they can all work well. France, often cited as the best health care system in the world, is technically multi-payer, but really only a hair’s breadth away from single-payer. In practice, this is a semantic distinction for most of us, since there’s usually little difference between universal single-payer and universal multi-payer. Because of that, in the US we tend to refer to all universal systems as single-payer.
None of these systems cover literally every dime of health care coverage. Canada, for example, is single-payer but doesn’t cover all prescription drugs. Different provinces have different rules. In most countries, it’s possible to purchase supplementary insurance to cover the gaps in the national system, something that’s necessary because
they all have various co-pays and exceptions.