I think this is very dependent on where you live and the school itself. I’ve never seen those shorts in the 9 years that I’ve had kids at primary school, but our uniform policy is very much ‘guidelines’ , and some boys do wear cardigans and all sorts of funky socks. I personally have always ignored the sock and shoe uniform guidelines (as have half the school) but I’ve never considered gingham shorts. A four year-old school starter in a bright polo shirt, book bag in hand, is going to look adorable no matter what shorts they wear.