Many people commit crimes by using transactions through their bitcoin goals to be difficult to trace and facilitate transactions, It makes the government difficult to formalize bitcoin because easily the crime can do a transaction but I am sure the authorities will not take silence they must have a plan to deal with all this.
It is not that difficult to trace those transactions,if there is any investigation against any user then nothing can do to save him,there are several examples where people have being caught and their bitcoins confiscated doing illegal things. So you cannot hide from the law if you are a criminal.