The problem with our health insurance system is that it's insidious. Our doctors spend ~25% of their time filling out information that only gets filled out to try to get insurance to not deny the claims, and hospitals have entire billing departments whose only job is dealing with the billing of our stupid ass system. The problem isn't just the ~15% that the insurance companies take directly, it's that since their percentage of profit is capped, they work to raise prices of the entire health care system so that their 15% cut is bigger. Insurance companies literally negotiate pharma companies to charge a larger amount to uninsured people so they get to take a bigger cut.
That's not all of the reason (some of it is higher cost of living, compare G20 vs G7 and the gap narrows a bunch). Some of the reason is because of US education costs, and immigration policies that make it harder for people to come and work in healthcare.
