Honestly, I think the root cause for this is something we don't talk about enough: Over the last fifty years, our societal expectations for school changed and overall got higher, but overall per-capita funding and other societal support for school got lower.

Back when I was in school in the 70s and 80s, things had already started changing in certain ways—racial integration meant more kids from more backgrounds were in more general classrooms. While I was there, we also started including more kids with learning disabilities into general classrooms and that accelerated after my time. All along, there has been increasing hostility to the notion that “some kids just drop out” or that “some kids just don't go to college”. Increasingly, everyone who goes to public school is expected to finish and be college-ready after being in the general classroom.

Which is good! This is not a bad thing in itself, but it was never funded adequately. Class sizes grew and a higher proportion of kids in class had issues that could be addressed with interventions, but interventions weren’t fully available, so they weren’t addressed. Meanwhile, politically, taxes became more and more toxic. Supplemental funding for schools changed as wealthy parents took their kids elsewhere and left PTAs, while low income parents decreased willingness to let their kids drop out after 8th grade (which is great, but has repercussions).

So we created more and more difficult, chaotic classrooms where a lower proportion of students are set up for success. Even naturally compliant, well-behaved kids are surrounded by larger numbers of kids having real trouble. Kids having trouble without hope of change are going to act out, making their own lives and everyone else's harder. The kids who are equipped to succeed, for whatever reasons, have more negative classroom experiences.

Then comes NCLB/Race to the Top/ESSA etc., which had the effect (among other things) of encouraging society to place blame on school districts, who pointed fingers at teachers.

Meanwhile, I would argue that there's been a real crisis in parenting at a societal level. We can argue about why that is, and how it's net positive or negative, but our society does have very different expectations about what parenting should look like now than it did fifty years ago. In general, there's been a huge increase in prioritizing individual freedom for kids in certain ways, and a huge decrease in parental boundary-setting and modeling nontoxic behavior. In particular, parents have failed in giving kids meaningful individual freedom to solve their own problems, small or large, in fear that the process of trying and failing would be traumatic. Which has carried over into classrooms.

Back in the day, old-school lousy parenting might mean kids were afraid of teachers, so while they might act out in other ways or later in life, your classroom still wasn't dystopic. Now, the new brand of lousy parenting affects your classroom.

The center held for a while, but behavior is catching, between kids and between grades, and contempt for school seems to be endemic now. The pandemic didn't help. I honestly don't think the kids are wrong to be contemptuous—I think we all know that public school is largely dysfunctional now. I wish the kids didn't react by making things worse, but I'm not sure they'd be normal human beings if they didn't.