pilots dress the way they dress for the convenience of others so they can recognize them faster from further away
That may be true but its not the main reason for the uniform. The reason is so the pilots act professionally in the cockpit. If a pilot is using his pilots license to fly free in the jumpseat for another airline, they will not let him in the cockpit unless he is wearing business clothes.
Why? He does not even fly for that airline.
The reason is simple. Airlines know that if someone in the cockpit is wearing shorts and a t-shirt, it will negatively affect the atmosphere in the cockpit. Since airlines require professionalism, all people in the cockpit, part of the crew or not, must be dressed appropriately.
Same thing in the courtroom. Imagine if the judge and lawyers were wearing t-shirts.
Its the same with us. If everyone is wearing colored shirts in the beis medrash, it affects the learning atmosphere. When people wear white shirts, there is a greater degree of seriousness. White shirts are the uniform of a yeshiva bochur/avreich. If you wear one outside the beis medrash, people will respect you as a yeshiva bochur/avreich.