Taxation depends on the officials who handles laws for taxes. It is true that bitcoin can be a job because it gives us incomes but most of the countries in this world are not handling bitcoin as part of their government so the government don't have the right to give tax on bitcoins. I am not thinking that bitcoin will have tax because the transaction fees are very expensive and if it has tax the fee will be more expensive and our income will be less and bitcoiners might decrease because of less income. Also, bitcoining is a digital job and it is hard to trace a person that is not paying that tax.