The reason for the high costs are multiple but in great part is because of the old style copay method of employer Sponsored insurance. If we needed a diagnostic test as a consumer we went to whatever facility was in network and paid our copay with no regard for the actual underlying cost.
This resulted in providers never having fo operate in a truly competitive marketplace.
Since the early noughties consumer driven health plans have become popular because they a) reduce the financial burden on employers and b) force us as users of healthcare services to be informed consumers. Of couse its not all about price, quality is a key part as well; however we are now seeing providers becoming more transparent with their pricing.
Many people do not realize that its highly likely their employer meets the full costs of the medical claims. All the insurance company is doing is processing the claim on behalf of the employer and Billing them on the backend.
This was one of my biggest criticisms of the ACA. It was health insurance reform and did nothing to address transparency of costs by the providers.