How did we collectively decide that it's okay for insurance companies to overrule medical professionals?

All of that cost savings makes US healthcare cost double what it does anywhere else in the world.

If we want to hold down costs then we'll have to put a greater focus on preventative care, stop expensive treatments for terminal patients, impose price controls on providers, and stop subsidizing drug development for the rest of the world. None of those measures are politically popular.

Some states have recently passed laws which limit the authority of health plans to conduct medical reviews or deny payment for services that providers deem medically necessary. This will reduce hassles and expenses for some patients, but it will also accelerate the inflation of insurance premiums paid by everyone else.