I just gave an example of running where it was about pushing, not if someone crossed a line. They even changed their decision after an appeal when other people looked at the same situation again.
And sports like football or hockey... Have you ever watched those sports? There are subjective calls all the time. It's objective criteria, but a human still has to interpret things like handball, which depends on if your arm is in an "unnatural position" or not. Those are largely subjective decisions and there is controversy around them all the time.
With breakdancing they are of course also judging specific criteria:
The winner is determined by a panel of judges, who score each performance based on five criteria each worth a fifth of the point maximum
It's really not that different.
Not American so perhaps I'm missing something, but doesn't it make sense tips are taxed? It's income, so why wouldn't it be?