That's just it. Nearly 200,000 people die every. single. day. Doctors have patients die all the time because some things can't be fixed, or can't be fixed within the constraints of "regular" medicine. One of those constraints is money. I didn't see where he took her to a clinic and offered the best surgeon in the world $10,000,000 to attempt the surgery. (And, remember, all medical procedures are just probabilities of repair not guarantees.) Because he probably would have gotten a different answer.
And, yes, it's intensely frustrating. In fact, I'm often glad that I'm not a doctor. I've run into cases where someone's home will cost more to fix than the home is worth. Often, for those people, it costs more than their life savings. It's the death sentence for the structure, and a pretty dire condition for the owner. Imaging that your only shelter is falling apart around you, and may collapse, but not only don't you have the money to fix it but if you found the money and did fix it, it would still be worth less than the money you spent.
As for the misdiagnosis, doctors are still humans and they still make mistakes.