Because of the way insurance tends to work in America, care providers tend to throw shit at the wall to see what sticks. In other words the first bill is always an outrageous amount of charges that may or may not be valid. Additionally there's something called a negotiated rate that an insurer has with the care provider, usually the care provider's bill does not show this rate but rater some fiction that not even those without insurance pay. If you look at the claims your insurer pays out to the care provider you will see significantly lower amounts than what's billed.

If anyone knows why care providers high ball the rates on bills when insurers have negotiated rates, I'd love to hear it. Is it something in the insurer's contract that gives insured the illusion that insurance is saving them a lot?

In any case I've received first medical bills in the many thousands of dollars only to have them go through four or five revisions before settling down to hundred dollars. This is because the first bill you receive reflects all of the claims to insurance (e.g. if your insurance covers 80% you're on the hook for 20%) but as the insurer and the care provider negotiate and revise the billing the price falls.

In my opinion it's a horrible experience for the insured and the added stress of the huge bills certainly doesn't help with recovery.