People like taking photos of themselves in the mirror, it seems. Especially with iPhones. The trouble with taking a photo in a mirror is that the image is obviously mirrored.
Here’s my idea. An iPhone, or other phone with a prominent logo on the back, can do some basic shape recognition to decide whether or not there’s a logo reflected in the mirror. It can then decide whether it’s taking a photo in a mirror or not and automatically flip the image if needed.