I don't find this strange at all and it's pretty normal in the Anglosphere. I went to a selective school and everyone had to wear the uniform in a certain way and style their hair. It's actually good because in some ways it's part of discipline and uniformity of all members. You have to remember some of these schools have a history going back to the 19th century and they want to create a feeling of oneness like you may see in the military. I'm sure now with time, their standards have changed a little but the idea of avoiding extravagant hair styles and being clean will still be there. Since beards are in fashion perhaps 16-18 year olds will be allowed to have them but it must be kept very tidy. I wouldn't send my kid to a school with low educational standards obviously but also where kids may have tattoos, piercings and funky hairstyles or where you can stick on pink dye. It's one step away from other distractions like drugs, alcohol, bunking off school, generally not giving a ****. IMO you have your whole life to do that and be an adult and make your own choices, school should be serious with organised fun to help guide your growing mind.
Also Johnson is the only one who has stated the obvious - of course they will overlook the rare poor boy suffering from alopecia and the thread title is more a reflection of personal insecurities.