A media interview is not a police room interrogation, nor a courtroom cross-examination. The interviewer (most probably) realises the question has not been properly answered but understands that they have to keep the interview moving. Also, if they go in too hard, it can have a backfiring effect of causing the audience to start sympathising with the person being interviewed (even though that person is clearly waffling and dissembling).<p>The interview is still effective in that hard-headed people watching the interview who need concrete answers and actual information will still draw their own (likely negative) conclusions.