Earlier quoted context omitted.
I don’t think people mean copy it in it’s current form, at least not forever. It’s just a catchy name to refer to a program where the government pays for healthcare, even though the current iteration of Medicare is hardly that. The idea is probably to expand the current system to everyone, which is better than nothing, and then work on improving it.
Hard to get velocity behind improving something half the voting population would rather be rid of, even if it's against the very same voting population's best interest. So it goes in the US.
I think the bigger issue is how the divide between the parties happens. People seem to demonize the other side based on a specific issue that is important to them and then extrapolate that view to all positions held by the party on the basis that "all [party] politicians are stupid because of their stance on [issue] so their ideas on other issues are stupid too".
For a generalized example, the divide is mostly urban vs rural (even in other countries). A major single-issue voting topic would be gun rights vs gun control. A rural person thinks a new gun control law is stupid because the law seeks to ban certain items that statistically don't cause many problems and they find utility in their gun rights (more likely to hunt, slow police response, etc). An urban person would think the new law is good because "why does anyone need that item" and they find little to no utility in those rights (less likely to own a gun, carry a gun, hunt, faster police response, more exposure to the negative news/affects just due to population density). Each side thinks the other is stupid on this subject. People then think, hey the urban person wants to take away my rights on guns on (what appears as) stupid reasoning, so I don't trust their proposal to federalize healthcare because their logic/brain must be deficient. Then urban people will say these dumb hicks "...are clinging to their guns and bibles..." so they must be too stupid to know what's good for them. Which leads to neither side actually listening to the concerns of the other like a community should and instead just trying to gain full control of the government to ram through whatever laws their side wants.