Again, other first world countries don't let the health industry get away with highly fractionized buyers which are powerless against service providers.

A few of the "highly fractionized" buyers are larger than most first world national health systems, so that can't be the major issue.

There are probably many factors, but there seems to be too little negotiating power on the demand side, even with the bigger insurances. And I assume the bigger buyers are getting better prices, right? Are those buyers bigger by the number of insured members or just according to expense volume?

Again, mostly the government should tell the industry to knock it off, mainly by empowering the demand side rather than the supply side.