> So in more than half the states people making just above a certain threshold get essentially free healthcare, while people making below it get nothing. In these states ACA has done almost nothing to help the very poorest.
The ACA, by itself, has done everything it could have to help the poorest, within the options that would actually pass the US congress (2009-2010). The Supreme Court said the ACA could not force the states to take the (federally funded) Medicaid expansion, so the state governments used that choice as a political party loyalty test. The state governments chose to refuse preallocated federal money, to help the poor, to show their loyalty for the next election cycle.
I too would have preferred a single payer system, but the ACA is what passed and the state governments have made their choice.