The analogy I was trying to make is that if you think there is an obviously undervalued company on the market that is crazily under-priced, you're probably wrong, and the market is probably right.

Similar, if OP thinks that there is an obvious case that Americans would back a completely socialized healthcare system, they are probably wrong, and the politicians that actually spend all their time talking to people and understanding the "market" of votes are probably right. One survey quoting a number of 70% does not mean anything particularly significant.

Medicare is by far the most efficient means in the US to pay for healthcare, including cash.

The problem with healthcare as a market is that it isn’t. We don’t allow medical professionals to decide that you don’t deserve blood pressure medication. But we do let bean counters decide that you get to die for lack of resources.

By doing this not only have we created a moral dystopia, but we’re wasting resources that we supposedly care about.