Single payer might be one way to fix that. But it could also bring with it some downsides—especially in the early years—that Americans who support the idea might not be fully aware of. And they are potentially big downsides.

First, it’s important to define what we mean by “single payer.” It could mean total socialized medicine, in that medical care is financed by—and doctors work for—the federal government. But there are also shades of gray, like a “Medicaid for all” system, where a single, national insurance program is available to all Americans, but care is rationed somewhat—not every drug and device is covered, and you have to jump through hoops to get experimental or pricier treatments. Or it could be “Medicare for all,” in which there’s still a single, national plan, but it’s more like an all-you-can-eat buffet. Like Medicare, this type of single-payer system would strain the federal budget, but it wouldn’t restrict the treatments people can get. Because it’s the term most often used in single-payer discussions, I’ll use that here.

The biggest problem with Medicare for all, according to Bob Laszewski, an insurance-industry analyst, is that Medicare pays doctors and hospitals substantially less than employer-based plans do.

Average Standardized Payment Rates Per Inpatient Hospital Stay, By Primary Payer, 1996-2012

“Now, call a hospital administrator and tell him that his reimbursement for all the employer-based insurance he gets now is going to be cut by 50 percent, and ask him what’s going to happen,” he said. “I think you can imagine—he’d go broke.” (As it happens, the American Hospital Association did not return a request for comment.)

The reason other countries have functional single-payer systems and we don’t, he says, is that they created them decades ago. Strict government controls have kept their health-care costs low since then, while we’ve allowed generous private insurance plans to drive up our health-care costs. The United Kingdom can insure everyone for relatively cheap because British providers just don’t charge as much for drugs and procedures.

Laszewski compares trying to rein in health-care costs by dramatically cutting payment rates to seeing a truck going 75 miles an hour suddenly slam on the brakes. The first 10 to 20 years after single payer, he predicts, “would be ugly as hell.” Hospitals would shut down, and waits for major procedures would extend from a few weeks to several months.

Craig Garthwaite, a professor at the Kellogg School of Management at Northwestern University, says “we would see a degradation in the customer-service side of health care.” People might have to wait longer to see a specialist, for example. He describes the luxurious-sounding hospital where his kids were born, a beautiful place with art in the lobby and private rooms. “That’s not what a single-payer hospital is going to look like,” he said. “But I think my kid could have been just as healthily born without wood paneling, probably.”