I have to disagree. Homework is not a way that "teachers get out of doing their jobs" obviously since we are generalizing there are exceptions. But homework is a tool teacher use to reinforce your learning.
Some people understand things instantly, and then do not need to do homework. But many others need the repetition to learn. Each person is different, but a school environment does not have the luxury of treating every child like a special little flower. They have to teach 30 kids and try to get them all to the same level.
The comment about being overworked is laughable. This is the easiest your life is going to be unless you marry rich or win the lottery. Life is like this, you will never not feel like you are overworked/underpaid/ect. And it only gets more intense. Relationships, Friendships, Jobs, Kids, All these new layers are going to be piled on in the coming future.