Exactly! I'm not a trained attorney, but I would have strenously objected that this was opinion or hearsay without any evidence to back up what "he" said they said in the oral interviews. I am shocked this is the governments habit, not to record oral interviews. For that reason alone those men should not have waived their rights and insisted on legal assistance.
Not video taping or audio taping an interview has been the policy of most law enforcement agencies . Unfortunately the courts have upheld this practice and the legislatures have been slow to act. This is now beginning to change. Maybe this case will help the criminal defense bar in their efforts to effect the change you desire. I think this would be an important step to determine if a statement was coerced or not.