I know that at my high school Robotics was not a course. We were a club, with members coming in when they could. Although, those who have one of the mentors as a teacher sometimes work on the robot, or robot related items. But now always, and especially not the computer science students who have much work to do(Robotics ruined my grades
).
Most of the kids at the school do not know about the team, and robotics pull in kids of all walks of life, so they might not always have time on their busy schedule for robotics. I know some kids had art as their chosen elective, so, not everyone is completely interested in technology.