This is true, but unless there is a real downside to one coach or the other, I wouldn't say it's unfair really. Win your fight and you get to train with some of the best MMA coaches in the world, no matter what team picks you up. Yes it would be better if both coaches were able to corner every fighter at least once before making a pick, but then that's not really possible in such a short time frame. Just because someone impresses you, doesn't mean they will listen to you.
The current setup is MUCH better than before, with the coaches picking simply based on 1 workout, and reviewing tape from other orgs.
Penn/Pulver was a perfect example. Everyone wanted to be on BJ's team, but Pulver clearly came out as the better coach.
The point is they aren't supposed to be cornering the fighters they are supposed to be observing the fights. So by cornering the fighters they are getting a one sided view of the fight.