Same reason why a lot of kids hate taking baths or showers. Or why they hated eating fruits and vegetables. But then once those kids got real jobs and started having to take care of themselves, they started eating healthier and trying to properly take care of themselves.
It's time consuming and takes away time to hang out with friends. Homework is annoying and hard to deal with. Tests are hard too. Also there are so many rules and that takes away freedom. School is also can be boring. You have to wake up early which is no fun. The food there is crappy. There are bullies. There is popularity. My list can go on and on about why I hate school.
the stupid azz amount of homework i mean i'm loaded i can't even like have some personal time once i'm done with my homework i have to eat then do chores then i sleep so it has taken over my freaking life!!!!!! sorry for the long answer i just needed to let that out :P