Schools Should Stick To School Matters - Not To Tell Others What To Do
In Ontario, Canada the Roman Catholic school system dictates school dress - blouses and skirts - the latter of a defined length. It has a 'liberal' attitude since trousers or pants and variations for necks (plain, frills, non-existent).
Stand outside any RC school at close of day and you will see many female students busily pulling their skirts way above stipulated level - rolling the surplus around their belts.
In VietNam school dress is simple (and economic). And it works fine for all family economic levels.
Females often wear white traditional Áo Dài, a popular form is a tight-fitting silk tunic worn over trousers. Áo translates as shirt; Dài means "long". The upper tunic has 'tails' which extend to the length of the trousers. The dress is actually two separate garments with a discrete 'air gap' concealed under the 'tails'.
Male students wear shorts (junior grades) and trousers (senior grades), a white shirt and a neck scarf along the lines of a boy scout.
Áo Dài and Western style clothing are quite acceptable for ordinary, daily, wear in the country.