I don't think we have any service in place today who deduct upfront tax amount from the bitcoin exchange. So all exchange procedure is tax free. It's on the owner of that amount who has the legal obligation to declare that amount to the tax authorities.
Also I am sure it will be illegal to evade tax. So I personally won't encourage to have such services to come into existence. Majority of the governments are already against crypto currency. So if we have any such illegal service running openly, it will further damage the reputation of Cryptocurrency.
Not only just talking for reputation of crypto but as an owner you should really think off that you would really end up on jail if you decide to evade taxes which we do all know that in which way we would go it would really be an illegal thing and don't really bother to build such business because you would really faced off lots of problems since you are going against on the laws which government do set on.
Yap but also depends on countries. In our place, we have a service that you could cash out without some payment or tax. An exchange site between btc and our currency that allows us to use any kind of banks or delivery services that is affiliated with the service. But oftenly its having maintainance just upon bitcoin increase, since it is the only service in our country offering a taxless withdrawal.