You can't see through it at all, so it gives 100 % privacy while still allowing the light from the bathroom to shine through into the hallway. (theletteredcottage.net)
The whole point of seeing through something is to see something through it. (firstthings.com)
They aren't as sheer as what you are thinking of, but you can see from the picture that you can see through them when closed. (mackenziehoran.com)