In addition to what has already been mentioned my old trainning school required PPL-CPL students to wear one stripe and the IR students to wear two. I refused to wear them after all what had I done to earn any form of rank except parted with loads of cash.
I also noticed the other day that at least one airlines operations personel wear one stripe.
Unfortunately their over use has somewhat devalued them. Rest assured that if the captain forgot them one day(highly unlikely), the aircraft will still fly just as well, any way s/he will still have the scrambled egg on his/her hat
