I mean the "mainframe model" of a single large system and many dumb terminals, now dumb terminals are named enpoints and the mainframe is someone else computer across the world.
The trust problem is easy to solve, with an open society: as long as payments got processed with open APIs and the government takes care of the frauds there is no trust problem. I do not need to trust a third party with eCash, I only need to trust my State protections.
That's still embrional but in FLOSS terms we have already more than enough, we just miss the law enforcing it and the schools teaching it to the masses.
I'm pretty sure I know where you are coming from, but I disagree with your interpretation.
The centralized trust model does not require mainframes connected-to by dumb terminals. We need only look at how Visa in its first few decades used carbon copy devices and signatures, along with eventual consistency across a network of mainframes, to gain market power.
"The trust problem is easy to solve" is laughable, as you well understand by the need for "the law enforcing it and the schools teaching it to the masses."
Well, easy to solve, means the solution is simple, not that reaching/implementing the solution is simple. Laws enforcing and school teaching are very complex, but the solution is damn simple. It's the road to it the complex part.
For health care the solution is making it totally public: all other the world the more health business exists the worst results and the higher cost you get.
There are aspects of a State to function that MUST be ONLY fully public. Again it's simple, in conceptual terms, hard to get applied in reality.
The trust problem is easy to solve, with an open society: as long as payments got processed with open APIs and the government takes care of the frauds there is no trust problem. I do not need to trust a third party with eCash, I only need to trust my State protections.
The idea is already tempted, see not only the historic eCash, witch are the modern GNU Taler chosen (it seems) by the EU for the digital Euro https://www.ngi.eu/ngi-projects/ngi-taler/ and https://social.network.europa.eu/@EC_NGI/111499172838284606 but also https://openfisca.org and https://github.com/CatalaLang/catala or few others alike.
That's still embrional but in FLOSS terms we have already more than enough, we just miss the law enforcing it and the schools teaching it to the masses.