It's going to the administration overhead. If you have to document everything and argue for every medical procedure and deal with 20+ different processes for filing claims then it takes time. And, as a provider, you have to pay someone to spend that time if you want to get paid.

It doesn't help that our healthcare billing systems are so outdated and broken. I once had a doctor visit denied with the reason code that it should charge the other insurance (for people on multiple plans). I was only on one plan, but my wife was on two. The doctor and I went through all the paperwork - my name was right, my birthday was right, my policy number was right and when I got notice of the rejection it had my name on it. Eventually we traced it to an error - not in my insurance company, not in the company that handles claims in this areas for my insurance, but instead in some middle-man company that was responsible for transferring claims between the two. Nevermind that all three companies claimed to be BlueCross BlueShield. This took over a year to resolve.