I think often when a student doesn’t care about something, they have been failed in some way. Often students are required to take classes the value of which has not been articulated to them in a convincing way, nor has it been demonstrated. A lot of required classes at the university level are pretty poorly run, and taught by people who are the least equipped to teach of the entire teaching pool a university has. And often the whole enterprise is treated by everyone else as a box to check off. So when that’s the environment and context, it makes sense that a lot of people check out. I think parallels can be drawn at the high school level as well.
There’s also the fact that students often have a limited amount of fucks to give. A person can look apathetic when they are juggling too many priorities — work, child care, elder care, mental health, and so on. Burnout resembles “laziness” so much that people who have worked themselves too hard can be blamed for lacking work ethic, it’s such a sad paradox.