The reason that her caseload is so high is because of all the pressure for "mandatory reporters" like teachers, child care workers, doctors, etc. to report any little thing that they come across. These 'reporters' are often worried that they will lose their jobs if they don't 'tell on' people.
A good point you raise here. I am beginning to see a pattern with medical reporters though using it as a club to force expensive treatments that are often unnecessary, using the threat of CPS to fatten their bank accounts.