Greed. The USA is a capitalist country so everything is governed by the almighty dollar. Government controlled healthcare would 1) put a ceiling on what the medical community can charge, and 2) increase taxes for everyone.
This is precisely what divides American politics over here. The right wants less government involvement in their lives, aka "let me make my money and leave me alone". The left wants more governement involvement "tax that rich conservative bastard and use his money to subsidize everyone else:.
They will never reach an agreement. Even very honorable attempts at improving the healthcare system have eventually faltered. When Obamacare came out, it was a God send. But as the years went by, the prices went up and the coverages got worse. It's almost as if the insurers were like "well if the government is paying for most of it let's just raise prices". Greed.
I broke my ankle in May. $35,000 for some pain meds and a metal plate and some screws, and sent home right after I woke up. I have an itemized expense list. There is no way on earth those items cost as much as I was billed. But they know insurance *has* to pay, so they inflate it.