Now all we've learned is that you define school bus in an idiosyncratic way, which already differs from the one I replied to (that definition stipulated that school buses also need to be owned or operated by a school). And if we ask 10 more people, we're going to find 10 more definitions, and I'm sure I can think of counter examples to all of them (for example, your definition would include parent-driven SUVs or any other kind of car frequently used to move children to and from school, which definitely doesn't count). Nevertheless, school buses exist, and there are vehicles that are definitely school buses. Maybe the problem is not with school buses, but with definitions.