You have no idea of the inner fight the woman may have had that morning and ultimately chose the skirt that was a couple inches longer despite her desperately wanting to wear the other one that made her look better. You coming to yell at her is telling her that the huge effort she made was worthless.
I’ve done that back in the day. I’ve almost cried as I put on a skirt that was maybe an inch above my knees as opposed to mid-thigh, and been so proud of the progress I’d made, and then told I’m being machshil the men. So the next day I wore the shorter skirt and didn’t think twice. If I’m going to be yelled at, at least I should feel I deserve it.