Good point. Most don't think this through. And I think the author would probably say that the earning, which could be overall better knowledge and understanding, is all too often less preferred than earning potential money one day or some other privilege. It's sad. When I taught fifth grade, this operant conditioning had already started. Even though we didn't really emphasize grades that much, many of the kids believed either a) they weren't that bright and the effort wasn't worth it or b) they were very bright and grades in fifth grade mean nothing toward college so why bother? And they'll all get promoted no matter what they did or didn't do, so it's always easier to take the low road.