No, they do have personalised outfits. Firstly, all their outfits are personalised, even their uniforms.
See their shoes, Antac's gloves, the inside material of the uniforms etc.
Secondly, their uniforms are just work clothes, designed for convenience to make them harder to gather by the moonies, and to prevent them from scratching each other. They have standard pyjama kimonos, and their customised winter outfits.
Also, Padparadscha customises his clothes.
Since they work all day and only need to change into pyjamas at night, they don't have any opportunity to use regular custom clothes at all. That doesn't mean that they don't know that they're wearing a uniform.