I think most medical professionals may agree with this: the U.S. healthcare system is built on rewarding volume and doing more things. It's an especially attractive field for clinicians who specialize because they have to do special things - with highly regulated barriers to entry.
And while there has been recognition by experts in recent years to push for quality and efficiency (since doing more procedures, especially those unnecessary, raises the risk of harm), the system has been slow to both incentivize this and lower the overall costs.