Thibgs on practice get much more complex easily.
You can't tax a transaction in cryptocurrency
11%-12% of the USA's economy is illegal activity. [2]
If you wanted to commit a crime or evade taxes, probably the dumbest thing you could do is record permanent evidence on a public, immutable ledger.
[1]: https://ciphertrace.com/2020-year-end-cryptocurrency-crime-a...
> Cash—anonymous and liquid—has long served as a tool for criminals. Cryptocurrency, with its similar characteristics, may likewise struggle to ever completely shake its bad reputation, despite illicit transactions making up less than 0.5% of Bitcoin’s yearly volume in 2020.
[2]: https://www.investopedia.com/articles/markets/032916/how-big...
> Estimates vary widely, but some put the underground economy at 11% to 12% of U.S. gross domestic product (GDP).
It still is something that facilitates it
And is the reason why some countries banned the use of cash after a certain amount
Wich again validates my argument about lack of regulation, or lack of actions from governments (ban), if we follow the logic for any other kind of currencies, including local/regional ones, specially the ones that are supposed to be competitive
[1]: https://www.taxlitigator.com/the-irs-confirms-its-great-eye-...
Unless all your financial activity completes within crypto transactions, you'll want to convert that to fiat one way or another and there's usually a KYC applied to it.