Jeans are seen as more durable - thought I don't get the attraction here in the subtropics. I always were cotton pants that wick away the sweat and such. I could die in nylon.
Jeans were always the required clothing for horseback riding, and day hikes growing up. With the girl scouts the leaders knew my parents and I well enough to allow me to substituted lighter cotton slacks. Sleep away wouldn't budge I had to have jeans for Horseback riding. The 1st year I managed to get the first class of the day, followed by swimming. That kept things manageable.
2nd year at sleep away camp they let me drop horseback riding(required class). Starting the 2nd week of camp, I was missing the classes after horseback riding, because I was in the clinic sobbing in pain. (This fact scared my parents and concerned my doctors because I rarely cried from the pain of a reaction)
With the nurse putting ice packs on my legs. After talking to my Mom, the nurse talked to both my pediatrician and dermatologist. They sent up topical and oral steroids. The nurse went to the head of camp and made her come see me in the clinic. Another round of calls to my parents and doctors they moved me from horseback riding to life saving. (I was too young for the certification, but a strong swimmer who more than held my own.) Water + sun helped clear things up faster.