Health insurance is a great example - a single payer system has much more bargaining power than everyone trying to negotiate for medical care at a moment when they'll die without it.
Of course, such a system is less efficient at extracting value from consumers, so I suppose your question requires an assumption as to whom a system is efficient for.
> Health insurance is a great example - a single payer system has much more bargaining power than everyone trying to negotiate for medical care at a moment when they'll die without it.
Also not sure that's the best example.
Singapore, Japan, Germany, Switzerland... all of those are multi-payer, but tightly regulated (which imposes equal costs across all actors, so that's coordination once again).
And I'd have to dig out the article, but I believe the above model (Bismarck) is better at controlling costs, and produces more positive outcomes as well.
The US healthcare system is a mess for a lot of reasons.
Healthcare being tied to employment is probably the biggest.
Maybe the second is a lack of any sort of common healthcare market? You can't just take "any insurance" and go to "any doctor"; instead, you have to navigate a maze of in-and-out-of-network relationships. It's like scheduling an appointment with the Mafia: "My cousin's dog-sitter's best friend's uncle's pool-boy Vinny knows a guy that can take care of your headache."
The adversarial relationship between insurers, patients, and care providers is also a problem. Insurers work very hard to screw hospitals and patients, so hospitals have insane overhead costs to fight against the insurers, and patients... oh god, don't get me started there.
Regulatory capture also plays in. And there's more, but yeah, it's a mess.
Fair enough, I mentioned single payer because that's the system I'm familiar with. The 'adversarial' relationship between insurers, hospitals, and patients is precisely the kind of market competition that theoretically leads to the best outcome though. GP's ask was simply about examples where regulation leads to more efficiency, it sounds like bismarck and single payer are both more regulated and more efficient (again, from the patient's perspective).
Of course, such a system is less efficient at extracting value from consumers, so I suppose your question requires an assumption as to whom a system is efficient for.