@EndovRhode
Very possibly. But it may also be because they are the easiest colour to see, provided the girls is not wearing a white skirt. I suspect white reflects the light better. Also, the give the best visible panty line because they reflect through the material.
Also, white is obviously the colour of purity, which has its appeal.
The girls in my school wore something similar to your picture. Except they also wore thigh length stockings that were usually just a bit shorter than the hem of their skirt giving a nice view of bare thighs again.
Yes, I had a very agitated, if not unpleasant, school life.