Why is there an expectation that it should not matter? Is it just childrens shows? In many countries you have to put a headshot on your resume, that seems very overt that attractiveness / looks does matter. In the west there is a large idealism over practicality sometimes.

Because we figured out that grading and selecting based on merit is better for society than grading based on subjective biases. I don't know what you mean by "practicality" here.

Where do you _have_ to put a headshot in a resume?