Well, if you got a uniform with classical British (or Japanese?) style blazer and cardigan, parents can decide to buy Ralph Lauren or other fancy brands. This still creates inequality in an environment where equality was the intent.

With the sports trainer-style uniforms, with flashy blue and white colors typical in China, with a unique print for each school (school name, school number, etc), there is only one store selling them, so everyone actually wears the same.