[Lucid:]

I've never seen any job listing ask for a photo when searching for myself, but my mom recently changed jobs and apparently her previous employer was asking for photos to hire her replacement.

The reason behind it is, like Quiet mentioned, to ensure that a front office/reception position is filled by a person who looks clean-cut and professional, capable of making a good first impression to clients who walk in the door, because that is an important factor of a reception position. HOWEVER, it's difficult for people in general to separate out professional-looking from attractive a lot of the time, once the picture is given.

I think it seems a lot more reasonable to make that judgement on professionalism during an in-person interview, where the candidate is also able to make an impression about the whole package of their behavior and mannerisms, not just physical looks alone.