Minorities and people with disabilities get disproportionately hit compared to their population.
Teachers are not mind readers and don’t know what is going on in a child’s head. Maybe the child is going through traumatic events in his or her life, maybe the child is being abused by parents or guardians.
Teachers are prone to errors in judgment, biases, and sometimes even prejudice. In other words they are humans like everybody else.
I found many more examples but this is sufficient to prove my point.