Wearing a tie has got nothing to do with tidiness. In fact, most of us look much less tidy when we wear a tie because we can't tie it properly and get it covered with soup stains.
Wearing a tie is a more to do with convention and fashion. Yes, maybe some want our instructors and airline pilots to look safe, reliable and conventional.
Personally I would rather see a clean, pressed shirt with an open neck and I wholeheartedly agree with Beagle.
One of the few modern trends I welcome is that it is becoming more acceptable not to wear a tie, even with a suit, and I welcome this with enthusiasm. Now I'm the boss in the company I work for, I do not wear a tie
..........unless I have customers visit because it's conventional! Urrggh!
Along with caravans and dangly things in cars, ties are pretty close to the top of my hate list.