 Because Democrats know they're going to go on CNN and MSNBC, and they're going to be allowed to recite their five talking points and bridge every question over to one of those talking points. And the interviewer is never going to ask a follow-up question or demand they give a straight answer. But if you're a Republican and you go on those same shows with the same hosts and try the same tactics, you're going to end up with the hosts just making a fool out of you.