> A good chunk of that can be improved with full employment. Capitalism also leaves a significant amount of storehouses/factories/etc unused because they're not profitable to operate.

You obviously do not have a lot of experience in manufacturing and technology. Factories can close for many valid reasons: inefficient process, lack of resources, lack of talents, consolidation with other factories, etc. These are all necessary for any kind of healthy systems.

> We don't have a large enough labor-force to operate at full capacity right now (I think including unemployed), we'd need more immigration for that.

Immigration is simply moving the problem to another country and is a major problem for developing countries where they people who can keep the lights on are leaving. Mass immigration also leads to lack of integration and social unrest.

> Reducing busywork jobs like advertising that suck in more labor in a pointless arms race will free up people for productive labor.

I'm not for useless marketing but it has a necessary function. Letting people know of potential better solutions is critical. A lot of problems are not known as problems that can be solved by those experiencing them. Also who gets to decide what is "pointless"? There are no good answer to this question, especially in a technological society. And even if marketing exists purely as a way to get an edge in market competition, removing competition itself always leads to complacency and corruption.

> We can take control of the actual physical plants and prevent them from escaping. Money isn't real, physical reality is.

Who is "we"? Most likely not you and me. And the idea that the plants and the workers will automatically keep working at "our" command is just pure fantasy. Organization is not tangible, yet you can't ignore them. Even if you remove the collective convention of money you will not eliminate the phenomenon of supply and demand and who gets to decide always lead to conflict, waste and corruption. And your phrasing of "prevent them from escaping" is very telling of what a dystopia that would be.

> Many countries have this, even poorer countries than the US

Yet Free Health care does not exist. Someone has to get paid, or be forced to stay to work by force, like is happening in Cuba.

> In any case, even libertarian think tanks found M4A would reduce the cost of healthcare by removing complexity from the administrative side at minimum.

If you think that a multi-trillion industry with very close relationships with those in the government would let that happen then you are very naive. The cost will be moved and renamed as the regulations, over-licensure and over-litigation will remain as the root cause of the problem. I live in a "free" health care system, it's more or less the same BS than in the States, but instead of worrying about money we worry about getting service in the first place after waiting hours or days or nothing at all.

> Pricing can be negotiated down via monopsony.

Keyword here is "can". I get it that you are unfamiliar with the horrors of the governmental procurement processes? Here's a hint: always taking the lowest bidder rarely leads to actual low prices.

> Not if the workers control the economy.

In reality only a handful of people can "control" a system. These people rarely tend to be actual workers or never have to work after they "control" others. This is a fantasy at best.

> They will not want their jobs to disappear unless they are promised placement and training. If those are provided, you may see even higher levels of automation as there will be reduced resistance to it.

Not everyone can "learn to code" or acquire new higher level skills. Not all automation leads to more jobs, and even if free market automation can make life dirt cheap and diminish required labor (which is kind of the case since a poor person probably has higher level of living than a king of a few centuries back).