We need altcoins as long as we interact economically over the net, with people we do not know (or simply with people outside our local communities). If we try to imagine what qualities a “solarpunk coin” should have, what are your thoughts? Do we know any existing coin, checking all boxes? This question is more about political economy of Solarpunk, then its technology.
Yes, that is more or less how the current system works, although there are structural incentives to hide government loans in various constructs and thus the 2-5% figure is understating the real extend. But even so, government debt at 100%+ of GDP tells a story about how taxes are not very vital for funding government actions.
I think there needs to be a bank that issues a debt voucher (more or less what money is) for a specific purpose, but that doesn’t have to be a monopolistic and state violence enforced single currency.
The 3rd world country example was just to point out that models of government exist that mostly source their income from resource extraction and other means that do not involve taxation.