You can only pay your taxes with the currency the taxing authority takes the tax in. But this does not prevent me from paying for my taxes with my labor; I just have to convert my labor into that currency first. The fact that you can't pay taxes in bitcoin or ethereum is not particularly distinguished from the fact that you can't pay for your taxes in goats, paintings, or the cleaning of clothes, nor is it particularly distinguished from the fact you can't pay United States taxes in Euros.