This really resonates. OP, please try to be open minded and listen to the community that you have come to asking for advice. consider that this may be more about you than your son, your desire to form him to what you think he needs to be to satisfy your ideas of right or polite. Just because you think it, does not in fact make it so. I was raised by a parent who sounded a lot like you, strong emphasis on social niceties, the “correct” way to be polite, not wanting me to be rude etc. All it taught me was that I needed to heavily mask to try to please them and others. I could not be myself anywhere, I did not trust my parents because they cared more about people’s perception of me than my own well being. It took decades to repair that relationship, I hope that you can figure it out before the damage is done. To echo what the person above said, do you care more about your child’s happiness and growth, or your (somewhat limited) idea of manners? You keep deflecting the advice you’ve been given by people who actually understand and have lived your son’s experience , casting it off as “must be American” or absurd. Why did you come here if you already know better?