Everything you've described is part of the problem. For some of it there's a better word: bullying.
Bullying is done out of malice. Encouraging somebody to enjoy a celebratory shot of alcohol after a big event is, in America, a show of friendship and camaraderie.
Yes, Americans can often be assertive, especially in a playful or friendly manner. That's part of American culture. As a foreigner, it's best to understand this.
I also note that your argument could be applied almost verbatim to women working in predominantly male environments. Or any other case where there's a minority surrounded by a entrenched majority. "It's just how things are" is not a satisfactory approach imho.
As an American, it's best to understand this.