> like in the rafters in the garage, or in various forts and hideouts 

Now imagine your parents tracking you going into the garage every time or to specific hideouts.

Privacy is in my opinion one of the most important human rights that exist and the most frequently diminished or ignored, especially around parent/kid relations. Hence why it is a part of the UDHR (universal declaration of human rights).

With regards to kid/parent relation we are often too lenient as a society. One good measurement that you can keep in the back of your head to judge a kids invasion of privacy is the following question "If this kid was suffering from abusive parents, would this allow the parent to intervene the kid reaching out?".