For me:
- System: Anarcho-Capitalism.
- Money: Hashgraph based stable coin, with Multisig wallets.
- Written Language: Korean Language- Hangul.
- Number System: Kaktovik Numerals.
- Calculator System: RPN
- Clock System: Swatch Internet Time
- Calendar: Solar Hijri calendar.
Not to edit your utopia, but a post scarcity society would be a dystopia, for more info about that, I invite you to check this Wikipedia article: https://en.wikipedia.org/wiki/Behavioral_sink
Post scarcity doesn’t mean high fertility.
did you read past the first sentence? about not living on habitable planets?