That's because you haven't really thought about it.
So the Greeks start bartering, what's the first thing they do ? Set up a website and unit of measure to swap (TEM's): https://www.bbc.co.uk/news/world-europe-17680904
That unit is tradable, you can transfer it (mail or message) to someone else. The record is kept on the internet. It's a peer-to-peer system where peers decide the value of the unit.
Looks just like a crypto to me without the ledger system for now. But it won't last long till someone incorporates that.
I get this often actually. ' I want real money, not something living in the internet, what happens when the electricity goes off? ' Then I can't get to my Bitcoins...
Indeed what does happen when the electricity goes off ? ATM doesn't work either. Banks can't issue money since they can't track it. Government can't print any either. Heck, sounds a lot like a crypto doesn't it ? Like it or not, all money now days is just data in a system. The only difference is who owns that system.
I don't know about you, but I am getting really tired of people punching buttons and then suddenly they own my whole life. If all of us can decide at once to tell them to go stuff their useless money and transacted peer-to-peer only all our problems would disappear almost instantly. No one would have to sell their time for less than the next guy and no one is going to donate money to war.
Crypto's are here to stay and they're going to transform our society in ways we can't even begin to imagine.
It's in it's simplest form programmable money, or put another way, a programmable contract. Something long overdue.