Be careful not to assume that implementation is much simpler than it actually is. Oversimplification is a political problem for both right and left when it comes to health care.
Also, definitely avoid conspiracy theory thinking that Democrats wound up with ACA rather than "single payer" out of corruption and malice, rather than realistic political consideration. That's another pathology. I don't believe there are any Democratic politicians who want health care to be more expensive and difficult! They want cheap, universal, quality, and fair. Duh.
Single-payer has had more public support (usually majority public support) than other routes to universal healthcare all the way back to and before when Bill Clinton campaigned heavily on health care reform in 1992; Democrats keep putting up complex, unpopular insurance industry kickback schemes instead, which end up easing Republicans effort to kill them either in advance of implementation (as with Clinton's effort) or afterwards (as with the ACA's progressive dismantlement since Obama left office.)