I think there is a sensible middle ground, with uniform.
I had dses at selective grammar schools, with very strict uniforms, and then we moved house, and their new school had more relaxed rules - there was a school blazer, but it was optional, and the children could wear a jumper, cardigan, fleece, sweatshirt or zip up sweatshirt, as long as I had a v-neckline or could be slightly unzipped or unbuttoned, to allow the tie to be seen. The girls had the option of trousers if they wanted to wear them.skirts, trousers, jumpers were black, shirts were white. Heels couldn’t be too high. It was a comfortable, sensible, reasonably relaxed uniform. It was practical too - I could buy fleeces for a tenner, and if they got dirty, I could wash them and dry them overnight, whereas the blazers they’d had to wear at the grammar schools cost upwards of £40 and were dry clean only.
This is a school that was near the top of the league tables in Scotland - the pupils were happy, well behaved, and did well at school - they didn’t need to have strict uniform rules to achieve what they achieved.
It is ridiculous for any school to prioritise the ‘look’ or uniform smartness of the pupils over their comfort - being able to put a coat on if the classroom is cold, or take a blazer off in hot weather. They are there to learn, and will learn best if they are comfortable. And I think it is perfectly possible to formulate a uniform policy that combines reasonable smartness with comfort and common sense.