Hope is that when big entities like the state or insurances have to pay the big bill, they have far superior means to enforce lower prices. That's not everything that needs to be done, but it is still useful.
They are actually pretty good at driving the prices down to something reasonable in most cases. While the headline prices are absurd, the prices actually paid by public and private insurers, whether Medicare or Blue Cross or Aetna, are much more reasonable. Not as reasonable as in much of the rest of the developed world, but the gap is not as gigantic as it initially seems.
The really big gap between the U.S. and the rest of the developed world on medical costs isn't the cost of individual procedures (once you've taken into account what insurers actually pay), but the much larger amount the U.S. spends on last-6-months-of-life "heroic care". If that were brought more in line with international norms, the overall cost-per-person numbers would be much better.
If I get table 4 right, people who manage to live past 85 years will have 1/3 of their health care spending after their 85th birthday (not entirely accurate, but a reasonable simplification).
I wonder though, even if the insurers can drive down prices, how do the insurance companies verify that they are only paying for services that are actually rendered? With the massive amount of medical billing fraud, I suppose insurance companies will invest in investigating and eliminating this behavior? Either that, or they will go bankrupt.
