“ If a male teacher showed up for work in shorts, or flip-flops, or a wife-beater undershirt, they would most certainly get called out.”
Point out the dress code where any of that is listed as appropriate attire for either gender in schools, and you’ll have a valid point. Every dress code I’ve ever seen lists dresses as appropriate attire for women, usually going so far as to specify things like “no plunging neckline”, “covering shoulders/shoulder straps must be two finger-widths”, and “skirts must be at least fingertip/knee/other arbitrary length”. Her outfit falls under all of these restrictions. In addition, my best friend is a teacher, and she told me about the “tests” she puts all her outfits through before she buys them for her job: the “bend over” test (if she bends over, do her boobs or butt show?), and the “reaching” test (if she reaches up for something, does her stomach or her butt show?). This dress passes both of these. As for her shoes, you need to get over yourself; just because women can wear heels doesn’t mean you get to disparage them for wearing heels. (I don’t wear heels by choice because I have ankle problems, but I see coworkers and other women rock them on the daily with no mobility problems.)
Finally, please tell me how dress codes are more restrictive for men. I seem to once again recall most dress codes I’ve seen, which defines appropriate clothing for men as a list of a handful of vaguely-defined items, while most women’s dress codes can range from “you must wear a dress/skirt” to “no sleeveless tops” to “no skirts/shorts above a given arbitrary point on your body” to “you can’t wear sandals, but dress shoes are okay”, etc. Often, dress codes for women are so restrictive that they have to go so far as to say “you can’t wear [list of specific items].” So tell me again how restrictive your dress code is.