It's interesting, as I have this conversation with my kids - ie actually let them know, there's actually no good reason for this, it's just a societal rule. However, I then try to explain that it is often advantageous to follow these rules even if it doesn't seem to make any sense, because of the advantages you can get by being cohesive in society. It's a good exercise, and also helps me think, there really are some dumb rules, and the calculus is weighing up when to disregard them.
That is exactly what I wish my parents did with me (my meltdowns usually started after few answers of "It's a tradition/rule") and what I do with my kid. I think for me growing up one of the most important person was my 5-6th grade teacher who instead of punishing me for doing something wrong actually took the time to understand me and tell me the logic behind why I shouldn't do it - so now instead of being punished for some specific silly reason I couldn't understand, I could get a better understanding of society and apply that logic to a wider spectrum of situations. And he understood that if he just explains me stuff like that there's no reason to punish me as it won't happen again anyways.
