Firstly, institutions are temple for education, skill & knowledge. We know that good education help a child to achieve success in life. School uniform helps pupil to keep in the mind that, he is in a place where he/she has to study. Maintain discipline, follow guidelines. School uniform is beginning of protocol. Moreover, you can see all the institution like Army, Navy etc has uniform, they looks like same, no difference in the candidates.
Uniform shows Unity, no matter a student is rich or poor, he/she has to come in specific dress code.