This is the "no new technology" argument again. This is an argument against every bit of technology that would increase productivity, because all the people it replaces would be out of a job and no new wealth would be added, it just makes things more efficient.
It's not though. It's not my fault if you can't tell the difference. We aren't discussing a
new technology here. There's no new technology of paying for healthcare that's been invented. An actual new technology
creates new real value. Real value is still the fundamental thing that the economy runs on, not dollar bills. Nobody has discovered a way to make real value out of "paying for healthcare".
Of course, even real new technologies do
cause economic shocks that harm people in the short term. Generally speaking, this is worth it and can't be stopped anyway, but this means that it is, again, still a significant tradeoff and it's worth knowing what you're trading off and having a plan for it.
You, not I, framed this as a question of whether single-payer healthcare is an easy and obvious solution without downsides.
The healthcare would just be better.
Hold on, how would the healthcare be
better? It's the same healthcare regardless of how you're paying for it. To get better healthcare, you either need to pay doctors and nurses more for more work - costing more money that now has to come from the government, which means it comes from taxes, which means everyone is forced to pay for it and everyone is a little poorer - or pay doctors and nurses the same or less for more work, relatively impoverishing them and reducing the supply of doctors and nurses available.
In particular, you seem to be assuming that more people would be able to get more medical services than they do now, because the government won't be allowed to refuse to pay for services it decides are unnecessary as much as insurance companies do — but since medical professionals like to feed their kids every day, they need to be paid for the extra work, which means this costs more money, and, by the way, it's extra work that highly-paid insurance actuaries have already determined is not worth the price.
We also have to think about what sort of new wealth health insurance creates.
Like I implied earlier, if you assume it provides no value at all and nobody ever wanted it, then you have to ask how we got into this situation where nearly everyone buys it and the government recently tried to make it mandatory in the first place. You can complain that insurance companies lobby the government to get that power, but they got the money they used to lobby the government, originally, from people buying health insurance because they wanted health insurance. Clearly it provides some value to people, or people at least think it does. It's fair to theorize that single-payer could provide similar value in terms of socializing risk, although it will do so less efficiently by design; but to imagine that health insurance is just a perverse creation of the Devil is silly.
It just takes money from people while deciding who gets to die sooner.
Will government single-payer healthcare do anything different? Decisions on allocating scarce resources will still have to be made, and sometimes it is not worth the cost to extend someone's life. Often, in fact.
Taking labor from that and putting it towards actually transformative labor would generate more wealth.
You can't just "put" people from one industry into another willy-nilly. People aren't fungible, and even if they were, opportunities to extract real value aren't infinite and returns diminish. What would you actually do? Make the middle-aged clerk ladies till cornfields?