I think he refers to the 1-inch gaps between the stall and the wall, and on the hinge side of the door. He might also refer to the 1-foot gap below the door or the half-inch gap by the door latch. American stalls are also short, so tall people can look right over the top.
Ohh I see. Yeah, that is a little weird but it’s hard to look in the gaps casually when you’re walking by without being obviously creepy (a friend tells me). Like it seems more visible from the inside where you’re stationary than from the outside in motion.
With gaps so big, why do we bother?