H. Gilbert Welch is a professor of medicine at the Dartmouth Institute for Health Policy and Clinical Practice and the author of " Less Medicine, More Health -- 7 Assumptions that Drive Too Much Medical Care ". The opinions expressed in this commentary are his.

(CNN) If the question is about health care, Sen. Bernie Sanders is the only presidential candidate able to give a short answer: Medicare for all.

In a world of health-savings accounts, interstate insurance sales, exchanges, silver or gold plans and accountable health care organizations, he dusts off a proposal from the 1980s: universal coverage by a single payer -- the federal government.

It sounds so quaint. But could Bernie actually be right?

Our current system of multiple payers is supposed to foster competition, which in turn is supposed to make health care more affordable, more accessible and have higher quality. How could a single payer ever improve on that?

Easy.

First, multiple payers multiply the complexity for patients. Sure there are many choices, but patients may not understand the tradeoffs involved -- often because they have incomplete information (Exactly who is in-network anyway?). While there may be some who enjoy all these choices, they are overwhelming for many.

And for those who might be eligible for financial assistance, there is another set of hurdles in simply determining their eligibility (What will your income be?). These hassle factors loom particularly large for those who have little immediate motivation to care about insurance -- the young -- the very group we'd most like to have it.

With a single payer these complexities disappear: Everybody is in, nobody is out.

Second, multiple payers multiply the costs for patients. All this complexity requires a small army to explain, sell, enroll and manage patients in plans --- not to mention the need to determine their eligibility for subsidies. Hospitals and doctors require their own small armies to deal with the different billing systems and requirements imposed by multiple payers.

And there's more: Different plans have different performance measures purporting to measure value and quality. While many might question the validity of these measures, no one questions their immediate effect: Providers need more staff to demonstrate that they are meeting the various measures of value and quality.

A single payer would drastically reduce these costs. Simply moving to a single uniform insurance claim has been estimated to save billions in administrative costs.

Third, multiple payers obscure overall system performance. Multiple, incompatible databases -- most of which are proprietary -- make it hard to know what is actually going on in American medicine. This is important for more than simply monitoring prices and utilization, it's important for monitoring safety.

The ability to monitor the safety of new drugs, new procedures and new devices is a critical function for any health care system. Get this: The United States had to learn about the high failure rate of metal-on-metal hip implants from the United Kingdom. While many complain about the FDA's ability to do postmarket surveillance -- the Institute of Medicine cited "substantial weaknesses" -- few point out the system weakness: the balkanization of data.

A single payer provides a single data system -- making transparent egregious prices, utilization hot spots and innovations that have gone awry.

Finally, multiple payers have too little power to deal with the really big players in health care. Big pharmaceutical companies, manufacturers of medical devices and diagnostic technologies, biotech firms, and now Google and Microsoft are all part of a vast array of investor-owned businesses with a shared interest in increasing health expenditures. Aptly dubbed the Big pharmaceutical companies, manufacturers of medical devices and diagnostic technologies, biotech firms, and now Google and Microsoft are all part of a vast array of investor-owned businesses with a shared interest in increasing health expenditures. Aptly dubbed the medical-industrial complex some 35 years ago by the editor of the New England Journal of Medicine, these businesses are in the business of maximizing their sales and revenues.

Our current fragmented system is fertile ground for this group. Trivial, or nonexistent, advantages can be parlayed into dramatic increases in prices via aggressive marketing -- as happened with Vioxx, before it was pulled off the market. More concerning is their interest in creating new markets: producing new patients by creating new diseases (like testosterone deficiency, aka Low T ) or selling the idea that the path to health requires testing yourself for various diseases.

A single payer would rein in the medical industrial complex. It would impose discipline in the introduction of new interventions, by requiring that they be tested prior to widespread adoption. It would then have the market power to ensure genuine innovations were fairly priced.

To be sure, critics would be quick to point out the side effects of a single payer: rationing, "death panels," and even the loss of freedom itself. If it's that bad, why is single payer the dominant strategy for health-care financing in other developed nations?

OK. We all know this is going nowhere. Even though a single payer would reduce overall health expenditures (not to mention lower premiums and out-of-pocket costs), it would mean more money would have to pass through the government ( read: higher taxes ). That's why you don't hear any other candidates talking about it. Universal coverage by a single payer is simply not on the political horizon.

But maybe it should be.