There are several possibilities for this, the most obvious one is that those at the top of Tether were able to buy the protection of very powerful people, a move that SBF tried to make but he was not fast enough to pull off.

Another possibility is that governments know what is going on, but they are letting Tether to get away with it to try to give a massive blow to this market once it gets even bigger, as there is no doubt that the collapse of Tether would have lasting repercussions on this market, and governments may use such circumstances to increase even further the regulations businesses and users alike will have to go through.