My mother growing up wasn't as bad as some of these examples, but she was more broad in the scope that she enforced the behavior. It really boils down to that she is obsessed with appearances. She wants to look the part of a good mother, so her son has to be smiling, because a smiling child, is a happy child, right? I did once post before about how I was paranoid at the funeral for my grandmother that if my mother was there (and she NEVER went to anything family related), she'd be snapping at me about how antisocial I was being during the reception.
Beyond funerals, she did really raise me to try and be emotionally dead, I think. Thankfully, I am cursed with being extremely emotional, but it's a chicken and egg sort of thing. I still remember the times she told me I ruined whatever the family outing was because I wasn't smiling, which automatically means I'm in a snit and being a brat. Heck, just typing all this is putting tension on my chest.