It’s a uniform in the sense that you wear the same clothes everyday, but not a literal, formal uniform like police or other prescribed outfit.

E.g. you decide that you will wear jeans and black t-thirts everyday. So you go out and buy 2 pairs of jeans and 10 black t-shirts. Then every day that’s what you get dressed in and this never have to think “what am I going to wear today?”

I wore brown overalls and white t-shirts for years as my uniform. This makes you more productive because you’ve now eliminated effort from another task in your day, making it more efficient and able to spend mental energy on other stuff.