It is hard to say yes to all mixers out there as there might be some of them that did not pass through all the necessary legal steps. But what I know is that the famous mixers such as chipmixer is legally registered. I supposed that means the government bodies such as the anti-money laundering and anti-terrorism agencies and others have given their green light to their operations. But this also means they are directly under the monitoring and surveillance of the government. The government can legally demand from them to undergo audit or to submit private company documents as deemed legally necessary.