"The rates that insurance companies pay are negotiated based on what they believe a hospital’s true costs are. But then those rates are jacked up an average of 30% to 50% to make up for money that hospitals lose in treating patients who don’t have private insurance — which is the majority of them. So to make up the difference, they overcharge patients who are insured. This practice is called cost-shifting."

I think this article makes a pretty good argument for Universal Healthcare