When we were in a car accident and had some hospital bills, we ended up having to go to court for the money (as the guy said he never actually hit us, the red paint on the bumper from his red car was a bit of a giveaway!), anyway when we settled, they called the hospital and for payment in full they halfed the bill! It is a bit of a con.
My Dad had come over for the birth of my first child (c-section $10000 +), he has had heart problems in the past, but ended up with a heart bypass whilst over there (about 5 blockages - NHS only saw 2 on a scan ), well is cost $100000, but worth the money (though overpriced!) as I do believe he wouldn't be here today had he not come over, probably had a heart attack on the waiting list. The insurance tried not to pay it, but as my Dad had called them and told them everything he had done (hospital scan and on a waiting for the appointment with the specialist) before he left and got authorization (mistake on there part), they ended up footing all but £10 or something crazy.
I think my biggest irritation at the US system, is when you have insurance, you have to check that everyone from the the guy giving the anesthesia, the hospital, the doctor, where the blood is taken to, are on the insurance plan, or you will be billed full price. I had a basic annual doctors visit, which was covered all by a small copay, ended up costing $200 as they sent the blood to a place that wasn't covered.