According to an article written for the Voice of San Diego, many of the
libraries in public schools across the city are not staffed. The reason
for this lack of staff comes from, suprise, lack of funding, but also from
union rules that state librarians, library assistants and techs cannot be
replaced by a volunteer or staff that would replace the job of the above
positions in any meaningful way. This causes the great support structure a
school librarian can give to a classroom, helping not only in research for
the students but for information for teachers.