The fact remains, western European national health plans cost less than half what USians are paying, even though the true cost may be hidden from individuals by employer or government subsidy.

Yep. And if we hadn't built the system we had, we might be able to have that here as well. But we did build the system we have, so we probably can't. It's not the end state that's infeasible, it's the transition.

One could argue, for example, that 220V is a better electrical system than 110V for basic household voltage. And it's certainly feasible to have a household electricity system at 220V instead of 110V - again, that's Europe. But there's no feasible way you would ever convert the US from a 110V to a 220V system. It would cause too much disruption to too many people for it to ever get support.

The benefits to single payer are much more pronounced than 220V wiring...but then again, there's a lot more stakeholders with vested interests in the current system (no pun intended) in healthcare. No, not just insurance companies, but all the medical providers that have made countless decisions and investments, great and small, based on the current general level of medical spending that takes place in this country.

The "Medicare for those who want it" proposal of Paul Krugman and Pete Buttigieg and (maybe?) Abdul El-Sayed is an effort to address that problem a bit, allowing for the possibility of a gradual transition rather than abrupt pivot to mitigation the disruption caused by the change. But that's not necessarily a feasible approach, for some of the reasons discussed in this thread.