Do you really think all healthcare - supplements, eye drops, family doctor visits, LASIK eye surgery - should be centrally controlled instead of using free market principles?
That's quite a claim to make. Cutting the entire healthcare industry off from the free market would only happen through government force.
Are you sure you're not confusing the US insurance system with an oligopoly?
Markets don't exist to magically generate low prices for consumers through competition, because businesses compete primarily for investor and shareholder cash, not to make end users happy.
The most reliable way to generate shareholder value is to create an oligopoly, and then squeeze consumers as hard as they can be squeezed - which is exactly why the US system regularly bankrupts participants, while regulated single-payer systems don't.
Countries with single payer also offer eye drops, family doctor visits, and LASIK... they just tend to pay less for them
You don't need "government force" to change how health insurance works. See Germany, many other countries. All you do is create a government healthcare pool that's large enough to cover risk, fund it, and give folks the option of using it or using a private insurer that will cost a lot more.
Especially since in the U.S., major changes are supposed to go through strict democratic processes that require broad consensus. Beyond good democracy, that's just human decency.
That's why I think there should be a healthcare constitutional amendment before the U.S. government gets involved. If California wants single-payer, they should go for it though.