Why could you be bothered to work hard on your tests but not your homework? I don't get the difference?
For tests, simply paying attention and listening to what the teacher said was enough to do well.
For many people, homework is completely useless and many US schools absolutely love overwhelming students with it. There are also kids who need to work jobs after work to support their family--busy work assignments are just punishment for them, and countless people I know suffered because of that. The ACT/SAT was a way for them to elevate themselves.