clacy,
I would say that health costs/coverage is a 3-pronged problem:
1) General increase in expensiveness of coverage with not the coordinating benefits in health.
2) Some people being uninsurable in the individual insurance market (thus presenting a huge risk to people of becoming poor).
3) Poor people, whether they're insurable or not, not being able to "afford" coverage. (I put afford in quotes because I think not being able to "afford" proper protection is a misprioritization of expenditures rather than an actual financial constraint)
I think most of us can sort of generally agree that these are broad problems with the current healthcare system... where we differ is what CAUSES these problems.
The problem with expanding Medicaid (even if we can accept the premise that it actually helps solve any problems) is that it is largely focused on the problem explained in #3. If I'm of modest wealth and income, but can't get individual health insurance because I'm uninsurable (or it would be super-expensive), then even an expanded #3 help could only help me once I'm on the cusp of bankruptcy due to an unaffordable medical event. If I get sick, I can't work anymore (hopefully I got a good disability policy), and I can't worki
Expanding MEDICARE would be something that would generally potentially help with #2 AND #3, and arguably #1, but it doesn't go away with higher incomes (though it does cost high-income-people more), so it would be a larger "takeover" of the system and thus less appealing to conservatives & libertarians.
I'm more of a fan of expanding Medicare than Medicaid. There would be individual insurance that you could get to supplement it, covering more "luxurious" medical needs (for lack of a better term). I actually love Warren Mosler's combo-platter of HSA's and Medicare for all once your expenses rise above a certain amount every year. I think phasing things out with income is one of the biggest sources of wasted time and "system-gaming" and moral hazards out there, and I also think it creates a lot of unnecessary classist animosities. The government provides roads & parks not just to the poor, but for everyone. If more of our government programs looked more like a citizens dividend and less like a disappearing benefit, it might cost us more on paper, but so much less in wasted time, moral hazard loss, and animosity towards those "others" that get a benefit that I've been phased out of. I also don't like when the government tries to use businesses as the provider of public benefits. Get employers out of having to deal with health insurance. I totally agree with conservatives on that. However, we all know that our agreement ends when we discuss how to handle it from there

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But this is just my opinion. I realize there are other models, and plenty of reasons to hate bureaucratic entities.