Why can Iceland setup and maintain a single-payer system but Vermont can't? Vermont apparently tried to setup a single-payer healthcare system, only to have various healthcare and pharmaceutical companies threaten to ruin them if they did so, at which point Vermont, a state not large enough to take them on, backed down.

Despite this, countries like Iceland have single-payer systems, and don't have to deal with things like nonsense pharmaceutical price gouging despite having only around half the population of Vermont, and six billion dollars less in GDP.

Why is it that Iceland can setup a single-payer system, but Vermont couldn't? What does Iceland have that Vermont doesn't? And how can these differences be generalized such to explain what the requirements are for a state, or country, or healthcare providing NGO to be able to run a single-payer system?
From what Wikipedia tells me on the Vermont case, the Vermont government feared increases in costs and taxes from such a reform. In the end, it boils down to what people/voters/decision-makers are willing to pay for a health care system they believe to be good for the people. Scandinavian countries provide lots of top-class public services (health care, child care, education) but also collect the highest tax rates in the world. Apparently, political will and public opinion in Iceland were willing to accept the price attached, which was not the case in Vermont. Beyond, it is possible that the move from the previous system was less drastic in Iceland, requiring fewer things to change.