Being in a bathroom is a vulnerable place to be. No one feels one hundred percent comfortable in one, except for maybe their own. That might be why so many people post god-awful selfies in their restroom, as if they don't realize they are in a porcelain palace. In this case, this woman is in a public restroom. You'd think that would be a clear indicator that you shouldn't take a picture. For one, it's a private place. I'm sure people trying to take a tinkle in the next stall don't want to hear the click of a camera.
The other thing that makes taking a picture in a public restroom a bad idea is that it will never make for a beautiful picture. People will always be distracted by the toilet behind you, no matter how clean it is. That is a very clean toilet, by the way.