Unpopular popular opinion: the money we use nowadays is made up of IOUs (I owe you). The money is created by central banks. Central banks don’t get money from anything; instead, they create money. The money then goes to investors, government and corporatios, and that’s why the rich become richer, and I, as a poor person, become poorer.
Also how do I save up perishables like potatoes for a big purchase? Do I have to set up a potato payment plan? What happens when I need IT services, but my profession is teacher and the IT guy doesn’t need my services, do I have to source something he needs from someone who needs my services to get his services? What if I can’t do my job without his services? Shit gets way more complicated without a uniform non-perishable national currency, fiat or otherwise.