What does 'subjective' mean in this context? That its effects can't be examined? In at least a subset of circumstances, they can be (unless having or not having, say, PTSD, is 'subjective'). Psychological evaluations in the legal system are much like physiological ones.

Let's say somebody has a sensetive finger, and breaking it causes extreme pain, according to that person. Assuming something like the eggshell skull rule still holds, should we dismiss his complaint or treat it as lesser because his pain is 'subjective'?

All harms are subjective, and not all actions result in equal harm to the victim. A concert pianist is arguably harmed more by having his fingers broken than an English teacher is. A professor once said he'd rather someone break his leg instead of a student falsely accuse him of sexual assault.