The INs and OUTs of Pluralism

I'll admit I crafted the title of this post because I have some pressing theological turbulence on my mind. More on that later. Today, I examine the odd use of line judges in volleyball.

It's not that I don't mind being a line judge. Hey, I've got a great seat close to the action and nobody gets in my way of seeing the game. What I don't get is why parents or athletes are used as line judges. I've heard so many vociferous rants from coaches and fans about biased officials.
"You just want the other team to win!"
"You hate us!"
"You're just mad because we don't pay you enough!"
"You're bald!"

Well, maybe that last one is not anchored in bias, but I have heard it before. Yes, officials miss calls just like players serve into the net, foul, step out of bounds, fumble or miss free throws. It happens. It can't be avoided.
But why does volleyball invite the opportunity for bias by using line judges who might happen to be parents or athletes from the home team? Little Suzy thought the ball was in so she aimed the flag down.

Now she's just doing what she has been told. "Be the line judge." That's all she's doing. She has no mean, bias bone in her body. Tell that to Joe Lungs who bellows, "That was out by a mile. What are you ___________? (Fill in the blank with blind, stupid, dumb, a homer, an imbecile. I've heard them all) In fact, Li'l Suzy is none of the above. Why give the appearance of bias by pulling people, no matter what they know or don't know, out of the crowd to make calls? No other sport does this.
It would be easy to place varsity basketball players in each corner of the court and tell them to call out-of-bounds violations during the JV game. You can do the same in football, soccer, badminton, baseball and, most likely, ping-pong. Put Mr. Booster on the football sideline during the school rivalry game. No? Well, how about placing Varsity Viola's little sister on the soccer sideline?
It's not done. For good reason, it's not done. Yet, in volleyball it's done in every match. Incredulous.