The answer to this and other similar incidents is the same as it has always been -school uniform. Girls in the UK don't get this sort of shit often because everyone knows what you can and can't wear right from the get-go (in the case of the majority of girls' school uniforms, either trousers or a no-shorter-than-knee length skirt with white or grey socks or black tights).

Dress codes can be used as bullying tools by both staff and students. School uniform can't.

School uniform allows shopkeepers to tell whether that tall, well-developed young woman at the counter is actually old enough to buy those cigarettes or not.

School uniform means the homeowner knows where to go to complain about the litte shits who wrecked his hedge.

Some may see it as old-fashioned, but the majority of UK schools still have a uniform for good reasons.

Sixth-formers in state schools, BTW, are uniform exempt. Some grammar-type schools ask for 'business dress', others for 'smart casual', but the majority trust their Post-16 students not to do anything too weird!