But in a case where either treatment choice could be reasonable, doesn't it seem like a better answer for the insurance company to defer to your doctor rather than their own assessment? Whoever is making that determination at the insurance company doesn't know you, hasn't treated you, may or may not have more expertise on the specific illness than your doctor, and as you pointed out the insurance company doctor is ultimately motivated by keeping costs low more than they are motivated by keeping you healthy.

Obviously I can see why the insurance company would prefer to be making decisions about your treatment, but it's not obvious why any of the rest of us should view that as an optimal or even acceptable way of running healthcare. It's essentially the car insurance model but with vastly higher consequences, and it's not great even when it comes to car insurance.