It's both. But there are also laws that limit an insurer's ability to push back. For example, ALL out-of-network emergency services must be covered, including a

It's both. But there are also laws that limit an insurer's ability to push back. For example, ALL out-of-network emergency services must be covered, including all follow-up work that occurs as part of being admitted due to an emergency. Out of network means the insurer and provider have not previously negotiated a rate. And emergency services are among the most expensive bills out there.