And they don't do anything to bring down the cost of health care treatment.
This goes to the crux of the matter. Everything done so far: Medicare, and even medicaid to an extent, The ACA, and now The AHCA, has been constructed, in their passable versions anyway, as though medical profits are the third rail that must not be touched. Touching that rail would mean certain political death, i.e., political campaigns could no longer be easily financed. Consequently, politicians have been driven to attempt the impossible: affordable, broadly accessible healthcare without undue affect on profits. Both political parties are doomed to failure, because they are both attempting the impossible.
Medical care pricing is inelastic, i.e., the buyer can't walk (in some cases that is literally true

). Text book, supply-demand equilibria do not hold. That's why of course all other developed countries have gone to either a uniform, very highly regulated, healthcare, insurance market, or to single payer. The lowest cost systems are all single payer. That does not mean necessarily that providers are government employees. It means that there is one, third party payer with power to negotiate prices and keep them down. On behalf of society, this party gains its control over inelastic prices through monopoly.
The naive will think that cost control in an essential, inelastic market is unneeded because the difference between free market price and the inelastic price can be made up by government subsidy. But it will be discovered soon enough that the required subsidy will grow faster than the overall economy, and will began to crowd out other essential components of the economy.
With the benefit of hindsight, we have all learned that when Greenspan, our chief banking regulator, learned of the abuses in the mortgage industry many months before the 2008 crash he did absolutely nothing. He was convinced that market forces would self-correct the excesses, more or less harmlessly, and markets would spontaneously return to equilibrium. He was wrong; they didn't.
Nor will the excesses in the American Healthcare market spontaneously, and harmlessly correct to market equilibrium. If there is any role at all that good government must play, this is it. Government must step in and force the necessary correction.
Is it going to happen? No, of course not. Will even a market with inelastic prices self-correct? Yes, eventually, of course. But it won't be harmless. We already see the first signs of self-correction, e.g., prescriptions filled in Canada and Mexico, medical tourism, drugstore immunizations, etc. These are all types of market correction that are being allowed to occur, and even encouraged to some extent. But these measures are too inconsequential to solve the fundamental problem. Eventually, unacceptable correctives can occur: civil disobedience, riot, mass unemployment, etc. This is avoidable. We, however, are a nation of crises. We won't touch that third rail until we are forced to.