[andlarry]

We do not have universal single-payer but we have a few very large government-run single-payer systems.

If you have an example of a country with a single program that has more effective outcomes for a population of similar makeup and size, that would be a useful comparison.

[dragonwriter]

A significant administrative cost benefit to single payer is not having to identify the correct payer, do coordination of benefits, etc.

With multiple “single-payer” systems in the same population (often serving overlapping populations with each other and private health insurance) you've negated that benefit.

You’ve also negated the market power advantage of monopsony purchasing by having multiple of them, and again having them coexist with private health insurance.

(And that's even before considering that while Medicare and some state Medicaid plans have single payer components, Medicare is not a single-payer plan covering the listed number of beneficiaries, but instead just under half are in the single-payer traditional Medicare, and that Medicaid isn't a single payer plan, or even a plan, at all, its a funding mechanism for state-operated plans, each of which may or may not operate entirely as a state-level single-payer plan.)

[anticensor]

> With multiple “single-payer” systems in the same population (often serving overlapping populations with each other and private health insurance) you've negated that benefit.

Turkey's system used to have that exact flaw (three single-payers, to be precise) until 2008. All merged thereafter.