It's not racial. And it's just as bad at high-income levels. And it's been happening for at least the last 20 years. My son graduated HS in 1996 at a mostly white high school in the San Francisco Bay Area - the kind of school where some kids get BMWs as a graduation gift and most kids go to top colleges.
The teachers then griped about not being able to control students because of parental intervention. One English teacher told me that in years past if he had disciplined a student, the student would go home and would also get disciplined by the parents for misbehaving at school. But now when he disciplined a student, the parent would come in and yell at him and go to the principal. He said a lot of kids would just laugh if he tried to discipline them because they knew in the end, there would be no consequences.
In this case, more like Juanita.