its purely unreasonable! one of the main reasons people use bitcoin instead of fiat is to do without payment of taxes and there's no point of decentralization if the government can put tax on bitcoin.
Tax evasion is a illegal thing, firstly. But only applied to the fiat economy for now. Thing is that you have to understand the reason why we have to pay taxes - for the development of the city we live in mainly. However it is not a perfect world so of course the taxation is going into other people' pockets but we are not the jurisdiction to declare whether it is correct or not, since we are citizens.
Bitcoin did not intend on evading taxes though. It was not what was in the ideology. Bitcoin was meant to be decentralized but that does not mean evading taxes. It means that bitcoin does not have any central institution controlling but.