Do parents file complaints these days if a teacher shows favoritism toward a specific student?

When I was in middle and high school, favoritism or picking on someone to make them an outcast happened quite often, so it wasn't a huge issue, but if that happened nowadays, people would probably file complaints, right? Since most parents these days are so sensitive to fairness and treat it as a golden rule while raising their children, I imagine there are many who wouldn't tolerate being treated unfairly at school..