Yeah, look at any number of things (including Medicaid implementation) that have been left up to the states and what a complete dumpster fire they are.
dylanmorgan
ITT: people who don’t understand that Medicaid is not Medicare, and that means-testing means a service isn’t “for all.”
Editing to add: Medicaid is funded mostly by the federal government, 69% vs 31% funding from the state. So even if it wasn’t means-tested (one has to have an income below a certain amount, or be disabled to a certain degree before qualifying) it would not meet OP’s definition, a single payer health insurance system funded by the state.
To answer OP’s question, a state funded single payer health insurance program would likely run afoul of the Commerce Clause of the constitution which states the federal government has jurisdiction over interstate commerce. UHC, Aetna, and other nation-wide insurance companies would absolutely sue over the state programs interfering with their right to conduct interstate commerce, and they would almost certainly win, even without a hard right SCOTUS like the current one.
I think that’s actually a pretty common view, just not often loudly professed by people with power or platforms.