What refs need mostly is nice black pants and the abilility to look like they know what they are doing ie; make bad calls but do it concisely with authority and make sure the bad calls are consistent. But nice pants are a must.
Perhaps its more to do with the age of the caged than wear with no fear. In my experience many young people tend to be a bit lippy regardless of what they wear. Happily this mostly gets beaten out of them the older they get