He tried early on to introduce single payer AKA HillaryCare ; it was, as matter of fact, as a matter of inescapable political reality, dead in the water before the negotiations even got started. He elected to not waste his capital on it and instead try for something which might- and did- pass.
The reactionary Republican Congress ( which does indeed make Nixon look liberal) made that perfectly clear as did the health insurance companies, who ultimately backed Obamacare.
YOu need to read a little more history to see how progressive legislation eventually emerges from the sausage factory. Social Security was originally 'fer widows 'n' orphans because that's all they could get through Congress. Then it was slowly expanded to be a generalized safety net for pensioners and the disabled etc. That's how things get done.
Yes single payer is the solution we are groping towards, but it's not going to happen all at once, unless you've struck on a way to make your Fox-watching Limbaugh-listening uncle Harry change his mind.
3) Cutting oil production IS progressive because it drives up prices and that makes renewables competitive, incentivizing investment and R and D in same. It's not that the technology isn't there, it's that it's not competitive against oil prices.
Sure, we could just declare global warming to be the greatest national security threat the United States has ever faced bar none and mandate renewable R and D, usage and production, and we should do just that. We could also force oil companies to build into the price of oil the costs they are inflicting on society. But then there's that little issue of your uncle Harry....