Saying this peice of cotton is underwear and must never be seen, and this peice of cotton is designated shorts and so is fine to be seen is nuts in my opinion
I don't think that's what people are saying at all. What people are saying is that if a girl's knickers are not up to the job of covering up bum cheeks and labia when the child is cross legged or upside down, then a pair of light cotton shorts will do the job. Nobody is saying knickers should never be seen. (Although I'd prefer not to flash mine) You can even buy actual nice soft cotton knickers that go some way down the upper leg, and they are just knickers and are fine, and nobody will be shocked by seeing those knickers. No shorts required if you have non-flashing knickers. It's when knickers are not doing their job of keeping private parts private that light exercise shorts come into their own. There are knickers now widely available to wear with dresses, for girls and women who suffer chub rub or don't want to flash their arse cheeks when they bend over. I know many people, girls and women, who have welcomed the advent of these comfortable undergarments, to wear under dresses.
This seems to me a whole massive fuss about defending female rights to 'wear what they like' I completely agree that adult women should wear whatever they want, wherever they want. They are grown ups with autonomy.
But having been a TA in primary school for more years than I care to remember,
I'm sure there would be a few mothers of the girls in the front row who would reconsider their child's undergarments if they'd had the sometimes sad and sometimes startling views of ill fitting and frankly inadequate knickers.
It's never the boys. I've never seen one willy in all the years I've been there.
I've seen more female genitalia than I care to remember. It's really not rocket science. Let the girls have underwear that covers their genitalia.
It's not anti-feminist to want to keep your private parts private.
And I have 3 daughters, no sons, and 5 nieces. So I'm fairly conversant with little girls and how their underwear can often let them down whilst they are completely unaware.