Surely it depends on the workplace, the task and the interaction with the customers.

If I dress smartly to interact with customers, then I end up dusty if I'm in the warehouse, so I wear company t-shirt and denims, but I wouldn't like to deal with a scruff like me in a posh clothes shop.

One of the local call centres insists that male staff wear collar and tie - to answer the phones. What's the point?