Slop.

From the article:

Anesthesia services are billed partially on the basis of how long a procedure takes. This creates an incentive for anesthesiologists to err on the side of exaggerating how long their services were required during an operation. And there is evidence that some anesthesiologists may engage in overbilling by overstating the length of a procedure, or the degree of risk a patient faces in undergoing anesthesia.
[...]
Critically, contrary to Murphy’s claims, this policy would not have saddled patients with surprise bills, if their operations went over time. The burden of this cost control would have fallen on participating anesthesiologists, not patients, according to Christopher Garmon, associate professor of health administration at the University of Missouri-Kansas City’s Henry W. Bloch School of Management.

“Say there is a contract between an insurance company like Anthem and an anesthesiologist,” Garmon told Vox. “What is always in that contract is a clause that says, ‘You, the provider, agree to accept the reimbursement rules in this contract as payment in full.’ That means the provider cannot then turn around and ask [the patient] for money.”

Now, In practice, how that would actually shake out I imagine is this: The insurance would only pay for the amount of "approved time", leaving a deficit for the anesthesiologist. The company that handles collecting payments for the anesthesiologist would send a bill to the patient for the difference, which will be a shocking amount, the patient will not know about this contract clause, and they will just pay it. One day, after a long time of this happening, someone with some inside knowledge will have this happen to them, they will refuse to pay it, hire a lawyer to sue the payment company the anesthesiologist uses, and have to settle this with them in court. The company will refuse to provide the language of their contract and terms with the insurance provider because it is a privileged industry secrete protected under law.

The only way I see this being remediated is through the legal system.