That sign is really for people who have never seen a "western" toilet.... many areas in the world have other type facilities....
Last year my S/O had some relatives visit from rural Szechuan,China.. While we were all eating dinner the night they arrived, one of her cousins excused herself to go to the bathroom... After about 30 minutes we were wondering if she was sick or something.... a bit later she sheepishly returned from the bathroom and explained she didn't know how to use the western toilet....
Pic taken from my old office at the Manhattan Br.... in the '80s
