Returning to “it’s not fair”: we agree, I think, that you could in principle count the proportions of punished boys and girls who, unprompted, make that remark.
I think you are claiming that this is of no use to anyone.
My view is that, if there was a difference, it could prompt further investigation: the difference would be a marker of some kind.
The further investigation might confirm your view.
Or, perhaps, it might suggest that there was in fact a significant difference between male and female psychologies.
I’d be surprised if you were to take the extreme view that, as we all come loaded with cultural baggage, it’s impossible for us to find out any objective facts about the human condition.
After all, you have your own cultural background — perhaps it predisposes you to think in this way