For many years, there were attempts at making national health care coverage, which finally passed as the ACA.
The ACA ("Obamacare") was controversial vis a vis constitutionality (it won by a five-four margin at the Supreme Court for a different reason than that given by the White House legal team) and its general usefulness, with mostly Republicans opposing.
You could expect that most liberal states would have their own "state-wide" Healthcare exchanges when debate was stalled on a national level.
Yet, California and New York (which are, nationally, generally Democratic / Left leaning states) among others, didn't have them.
Why not?