> Fortunately, complementary currencies are now legal in just about every country, as evidenced by the popularity of cryptocurrencies, one form of a complementary currency.

In many countries, cryptocurrency is considered a commodity - not money - and therefore disposals (where a cryptocurrency is given up in exchange for something else) are taxable events.

This is quite inconvenient and complex compared to money, and only less so if you are fortunate enough to be using a cryptocurrency that is pegged to your local currency (eg USDC or mUSD in place of USD).

Furthermore, if I understand it correctly, the purpose of complementary currencies is to act as a form of capital outflow restriction: you have a limited amount of capital in your town, and you want it to remain in your town alone. A complementary currency, which can only be spent locally, restricts the outflows of capital and allows it to remain local and do useful work multiple times within your town rather than potentially enriching other towns.

Cryptocurrency doesn’t intrinsically do that at all, although there are certainly some tokens designs that can replicate it eg LP emissions on decentralized exchanges.

All of that said the most interesting experiments in currency/tokenization/etc are happening on the blockchain. Are they successful? It's mixed but I think blockchain allows people to easily try new things and it's been fascinating to see. For example (and I'll do my best to explain in a sentence or two):

- Bread Cooperative (https://breadchain.xyz/) - Active project. Creates a "vault" for your stablecoins where accumulated lending yield is distributed to non-profits based on a weighted vote.

- Circles UBI (https://circles.garden/) - Active project. Creates a network of wallets where a wallet's humanity is proven through economic means. Each network participant starts receiving a token of the Circle's native "currency" effectively creating a network of humans in which money creation is evenly democratized.

- Reflexer RAI (https://reflexer.finance/) - More inactive. Created a "un-pegged" stablecoin. Meaning something that is not a dollar but is stable. It's been described as "capital inefficient" meaning you gotta put a lot of collateral in to get mint RAI, which appears to be a fatal flaw. But I love all experiments in unpegged stable coins.

And in general the ecosystem is full of all sorts of communities with their little currencies that have all sorts of properties like stability, minting mechanisms, distribution, voting power, you name it. It is not all good but I think it's fascinating.

Addendum: Yannis Varoufakis (economist, author and briefly Greece's Minister of Finance) has a book in which he outlines an example of a utopian economic system. (Great book). While being generally anti-crypto he bases the central bank around a transparent blockchain "smart contract". Any money printing by this contract is easily trackable and obvious to others and the yield generated from central-bank lending is distributed to all citizens. He has recently pursued this as an actual goal, albeit in a different form (I have yet to get into the details): https://monetarycommons.com/

It's not money because there's no associated liability.