Hmm, you have to remember though that the uniform forms part of the overall organisational image.
If an employee feels comfortable in their uniform and has the perception that they look professional in it, it has a substantial effect on mental attitude.
Hence a number of the large corporates have reverted back to a suit & tie dress code as opposed to the everyday is casual clothes day attitude that was present a few years ago.
God, that organisational psychology course I did really came in handy for something afterall! Now I just have to find a use for algebra and I can die a contented man!