I'm a dual citizen, currently living in the States. I can say with certainty that there is some lingering fear mongering around single-payer healthcare. Lots of Americans have this idea that healthcare in other countries is terrible. I've had people flat-out refuse to believe that hospital wait times for deadly emergencies don't regularly exceed 6 hours in Canada.
I'm guessing that the people profiting from the current system in the US have done their best to convince everyone that it's the best way.