Uhmm if you don't know even properties or assets have taxes, assets such as real estate and stocks are taxed under capital gains while money coming from your job or other ways of earning money are taxed via income tax. So even if Bitcoin is counted as a currency it can be taxed by two ways which is either capital gains or income tax or even both. It will be capital gains tax when your BTC increase its fiat currency value and it will be income tax if your earn BTC as a form of payment, also you can be tax with its capital gains if you decided to hold it rather than converting it right away to fiat currency. The bottom line is no matter how you earn BTC or any other cryptocurrency the government will always have a cut on it by way of taxes.