Everybody is insured. If you can't work, you are insured. If you are ill and not employed, you are insured. If you are a baby just born, you are insured. If you are a student, you are insured - either through your family or on your own. If you receive social security payments, you are insured. Basically everybody, 99.9% of the population is insured.

If you are employed you pay to the health care insurance or sickness fund directly. Your employer also pays. The money is not collected by the tax authorities and is not administrated by them. Still it is public regulated system.

If you are privately insured, you pay directly to the private insurance company. This may provide additional services or a better quality.

OTOH if you are not member of a private insurance, then you still can get additional insurances from those. For example you can insure yourself privately for certain health care services if you travel to foreign countries.

In Germany we would only consider something to be a tax, if we pay somehow to the tax administration. For example if one is a member of the catholic church - which is voluntary - then one will pay 'Kirchensteuer' - 'church tax'. This tax is collected with ones usual tax payments, by the tax authorities - for the catholic church. If you are not a member of a church, like the catholic church (or some others), one does not pay this tax. If you are a member of a free church, then the tax authorities don't collect money for them. If you want to be a member, it is expected that you pay more or less 'voluntary' directly to them.

> I take it that as a German, working in Germany, I could not "opt out" of all of this and just take my chances?

You could opt out of the public system, and get a private insurance company. But once you have done so you can never re-enter the public system. And private insurances are cheaper for young people, but significantly more expensive later in life, so much that you’ll end up paying several times more over your lifetime.

Car insurance? Most US states do require a minimum level of insurance if you have a car.

You can't opt-out completely. Some people (including probably most HN readers) can purchase highly-regulated private insurance instead but even that isn't possible for the vast majority of the population.