I wore uniforms back in 96' and 97 in a private Jesuit school in Montreal.
We still had choice over out clothes, but you either had to wear a suit jacket with shirt and tie and slacks or in the winter turtle neck/shirt tie and Vneck with slacks.
Even though I am rather large now for the norm, I was one of the smallest there back then, and got beat up regardless on a rather regular basis. Clothes don't make the difference.
Then don't keep you in line and keep you from failing. The smart kids who refuse to do your homework do.