The problem is the morass of laws we've accumulated around healthcare over the years for various reasons that now interact in complex ways that nobody foresaw. Like the law designed to make Medicare or Medicaid (I forget which) drugs cheaper that ended up making it illegal to give free birth control to college students.
We also have the laws from when people believed that competition increased costs and so tried to ban competition between hospitals. Or the committee that sets doctor's reimbursement rates for Medicare procedures based on the *$%@# labor theory of value. And the laws designed to prevent people from overcharging Medicare that means that everybody has to worry about those rates across the industry. Or the way that the makeup of that committee means that primary care physicians gets shafted.
And the fact that we allow so few schools to teach medicine means that they can charge an arm and a leg, which means that those poor shafted PCPs need the kickbacks they get for assigning specialist care in order to pay off their student loans and malpractice insurance.
And I could go on.
And now we have this system that's incomprehensibly complex. So Congress has no way of figuring how to fix it on their own. There are people who've spent years figuring out how all of this works, but that's their job and if the system was actually fixed their job would be gone and that understanding they spent years acquiring would be useless.
Which isn't to say that this is entirely hopeless. There have been some efforts at the hospital level like Kaiser Permanente's to ameliorate the perverse incentives in the system and capture some of the value unlocked by that. And there are some laws that could be changes or repealed (like the one against hospital competition) without really breaking anything. So I think that gradual reform might be possible, but it's going to be a long road that doesn't particularly involve the issues that people tend to talk about around healthcare.