Universal healthcare reduce individual costs, ie is "more efficient", but raise the demand. Even if it makes each act 50% less expansive, if the demand is 4x more, that'll still be 2x as much in total - it is less efficient on society as a whole, because it's not a productive use for money.
My point is not that resource acquisition is the highest goal of human beings, it is just that money spend of such thing can not be put to a better use. It's good to spend money on feeling good (healthcare), as long as the other way the money is spend provide growth.
I would favor universal system if I saw convincing evidence that people would not overclaim (ie seek treatment for minor ailments), and if they were respectful of the regulation system which has to exist if they can't self regulate with their own money. I see just the opposite, except maybe for the UK, but I don't have any experience with their system, and I don't know if they run a deficit. Anyway, if there is a special case, it certainly is the UK.
Even worse - I've noticed a troubling trend. Apparently "generosity" or "social spending" is correlated with group identification - i.e. people who self categorize as different groups (based on religion, ethnicity - anything) are less likely to favor social spending, maybe because it could favor the other group. I don't have evidence for this - it's just something I noticed when people are debating about social systems.
It is troubling, because most of the countries implementing universal healthcare are also running active immigration programs, which helps balance the cost of their social system. But if the trend is real, this countries will voluntary reduce their social spending after the initial period where immigrants footed the bill - leaving them resentful.
My hypothesis is that countries where diversity increases (such as countries in the western EU) will reduce their social systems, while countries where diversity plunge (don't know if there is any at the moment - but the province of Quebec in the 1970 is the closest example) will increase their social spending.
Please give some references for the US, but from quick calculations adding a trillion of deficit every 5 years looks like a bad idea (and I'm only talking about public healthcare in France- many people pay on top of that private insurance since the public system doesn't fully cover all the costs - money spent to purchase service from such for profit companies should certainly be added if you want to compare healthcare systems)