#I think most countries just didn't decided yet how to tax Bitcoin holders properly and how actually identify them. But taxes will be in every country in a few years.So the government can provide and assess taxes to be paid and the tax income arrangement on bitcoin lies with the government tax of each country.
Most actually simply impose taxes on businesses. They all end up there one way or another, so it is an efficient way to tax. Businesses themselves impose the taxes on their customers so there is no need for governments to track and trace.