Yearbooks are done differently at each school. For some it is a high school credit class, for others, may be volunteer students with lots of guidance, or not guidance at all. With teacher and staff turnover in recent years and student engagement lacking due to missing a couple years of mentoring by older students these electives or after school activities are hurting.
Managing hundreds/ thousands of photos is tough for professionals, never mind teenage free labor. Not being in the yearbook, is tough on students, but they usually understand…it is the parents that struggle more with mistakes/omissions.
Obviously, if there was a deliberate move to not include the student that is an issue.