The school and teachers do prepare for these events, however, and I encourage you to attend and invite another parent along next time. Research has shown over and over that the schools that are most successful have a high percentage of parent involvement. Attend meetings that you are interested in and then seek out organizations within the school. If your child is interested or participating in activities such as band, sports, or any other afterschool activity, you may want to support that group.
The fact that your daughter was "mortified" was due to your being the only parent and not because of your interest in her school. Find out what kind of involvement her friends' parents have. It is fairly typical that middle school children would prefer if their parents were not seen in public. Don't be alarmed. Keep telling your daughter that you are interested in everything about her, and show her your support.