There must be thousands of scenes from US dramas set in school hallways lined with lockers. When you’ve got 8 classes (which we’ll get to later) you tend to have a lot of books, and carrying them around all day would be pretty painful. So you need somewhere to leave them where they’ll be safe.
Lockers make perfect sense, but there are some countries around the world where lockers seem almost alien. A lot of countries in the Asian Pacific only have to carry their computers around anyway and have no need for a locker. Where would the good old American high school drama be without lockers? A lot more boring, I think.