> I am not sure that decentralization is less efficient.
So, maybe your vision of focussing on the essentials - food, shelter etc rules out microchips which definitely benefit from specialised employees, and centralised operations; but that will rules out a lot of future advances wherein microchips are embedded in everything, or at least until a suitable de-centralised equivalent is found.
In the meanwhile, I'd worry of the problem of being over-taken; i.e other free nations that do subscribe to capitalism and the centrally managed resource model outcompete and invade you - which is arguably the fate of many of the American tribes that lacked the weapons to fight colonialism. Not having microchips can cripple any modern army/defence-force, least of all an ad-hoc decentralised one.
Also, things like injection moulding might be out to - modern products manage cheap mass-productions by producing expensive master tools, and using them to churn out millions of items - unless tribes specialise on produce (in which case we are back to trading goods and services) then no more of these items either.
> the machines are serviced by the members of the collective
This limits how complex these machines can be, and or numerous - which in turn limits how prevalent. Also, back to the question; are all the machines going to be bare mechanical contraptions of wood and steel, or can they contain silicon - which unless you have an answer for fabrication/manufacture, cannot be repaired forever, and will need to be replaced. Modern open-source is parasitic to the capitalist economy around it - 3D printers still contain Atmel mcus and intel cpus, not to mention the motors, rotors and precision belt/shaft/bearings.
> Health care is to me essential but these things would vary from region to region based on cultural ideals and material conditions.
Where do the doctors come from? Are we hoping as many people are willing to spend a large amount of time training, or being trained, as surgeons; as there are people who need surgery? Will we still punish negligent doctors, at risk of no-one wanting to bear the burden of liability if we did?
What about law? Would anyone want to be a lawyer if it wasn't well paid? Would many current lawyers do law if it wasn't well paid?
> I am an engineer and I love to fix machines
I feel this is a strong bias colouring your opinion - many engineers love their jobs, and the things they fix/design/repair/manipulate. You seem to be arguing for a society of engineering, based on the manufacture of things (machines and their products) - but society needs more than things, and people are often motivated less by things too; by wealth and status, for example; I'm not sure everyone can find the same joy in engineering as those who select for it.
> Doctors or teachers often feel similarly
Not so sure that's true. Many engineers care more about the things than the help they provide people, and I'm sure doctors are the same too. If feels too much that everyone needs to subscribe to the same philosophy for this to work, and even then there will be some roles that are neglected in favour of more "engineery" ones..