I don't live in the US. My knowledge about the system there is basically just from hearing stories and reading articles.
But I know the german system very well and if I compare the two systems I just don't see the necessary foundation in the US for such a system to work.
For example, there is strong governmental oversight necessary in several are of the system. There needs to be consistent political will and know how behind the systems, or the system falls apart. This isn't just a system that can work on a simple majority.
Its a community effort and it starts at the small grassroots (every individual) and goes up to the highest levels of politics, there has to be full support from everybody.
But currently the idea is rather rare in the political establishment in the US.
There aren't experts who could come up with a comprehensive law. European nations look back on decades of experience with universal healthcare system, there are many experts who know exactly how they work, but the US doesn't have people like that.
The know-how has to come from somewhere. No big money interest will do this for us this time, because they don't want it, they'll even fight it every step of the way.