There's something Asimovian about the British legal system.
tl;dr it's argued that having a recognisable uniform, no matter how bizarre, levels the playing field and provides a sense of professionalism.
Still in England, think of queens guards. Those red bear hat uniforms make them seem like silly tourist attractions that you can tickle for a selfie, not professional soldiers that you shouldn't mess with. In that case, maybe that's OK. For barristers, that's not what you want.
There's a case for uniforms, but it's doesn't extend indefinitely.
A black toga[1] is traditionally worn in Dutch court cases by all the legal masters, but it does look rather stylish.
[1]: https://www.win-nieuws.nl/wp-content/uploads/2017/04/Student...