In my country the threshold is 40 EUR/transaction for a total of 120 EUR/year.
Between this tiny amount and the amounts needed to buy a house there are plenty of use cases for wanting to sell Bitcoin for fiat without KYC.
In the UK you don't pay CGT on realized gains of up to ~£12,000 / year and if your sale transactions total to under 3x that you don't even have to declare them.
That, however, is going to be halved from April this year, and halved again from April 2024.