Laws Between State Lines
Unlike other countries, the laws change between US state lines, and that doesn't make much sense. There should be continuity within one country, but that isn't the case within the United States. A crime committed in Pennsylvania could result in a warning there, or years in prison somewhere else.
Talking Loudly
Americans are known for being stereotypically loud talkers. They tend to overpower conversations and take obnoxious phone calls in public spaces like busses or cafes. It seems to be a national problem that other countries don't seem to have.