I’ve noticed everyone has cauliflower ear. How?

I recently got into NJPW and something I noticed is everyone has cauliflower ear. I do Jiu Jitsu and not everyone there has it (those who train consistently and regularly) the worst that happens to me is my ears might turn a but purple and inflamed but it's wild that they all have it.

I wonder what they make them do at the dojos? Anyone have info on this?

by CatDogBaseball