I volunteer at my kids' middle school XC races and point runners in the direction of the finish line. It isn't a very high-stress job, but it is really important. My job is to make sure the kids don't run off course. If a parent or friend or coach or spectator runs onto the course and waves a flag and causes a disruption, I ask that person to please move off of the course.
I do not live in LA, but if I did I might volunteer to help the LA Marathon RD next year.