The majority of traditional work clothes worn by white collar workers etc. are by and large indistinguishable. By that I mean that if you were to pass them on the street you wouldn’t know if they were on their lunch break or on holiday. In the UK in particular, office staff are expected to dress smartly even though they may have no contact with anyone outside of their environment. Some “modern” companies have begun to relax this strict rule and allow their staff to wear whatever they please (within reason).
This concept, which is very slow to develop in the UK, is widely adopted in the USA, where workers will be very informally dressed even if they are meeting important clients. There are differing views on this. Some say that a person will do a better job, be respected by his subordinates and taken more notice of by his superiors, if he “looks the part”.
The alternative train of thought is that if you are more comfortable wearing leisure clothes such as jeans and a t-shirt, you will be more relaxed and henceforth get the job done more efficiently. Some companies try to keep their staff happy by having a “dress-down” day every Friday, for example. This allows workers to show off what they may never have a chance to, on the other days of the week. It can also have it’s downside in that poorly paid or one-parent workers may struggle to keep up appearances on such occasions.