Don't know about PPL's...however, I do recall sitting on ground at DXB years ago in a B707 freighter, with a flight delay (late cargo) and the First Officer, now getting rather hot in the mid-summer heat, wanting to strip down to his underwear.
He did so,whereupon, I took a photo.
I signed on the back...best landing I've ever seen, and presented it to him some two weeks later.
Epuletts.
Not needed for folks that truly know how to fly...and young F/O Tay was the best of the best.
He could roll the 'ole B707 on every time.
A superb pilot...speaks volumes of the SQ training, at the time.