Because the margin is so huge in healthcare products and services, especially at hospitals. Hospitals rely on astronomical margins on certain payer classes to subsidize uncompensated care costs.

The point is that providers are far more invested in maintaining the huge margins rather than minimizing the cost.

Problem is the payer mix has been shifting from insurance companies to patients via high deductible health plans over the past decade so it's starting to wreck their margins, even though the cost doesn't change.