From what I know, it's easier for a caster to put a flight spell on an object and control that, rather than on themselves. In their paranoid stories of spellcasters, they fly around on brooms like scary witches, terrorizing the public. But a real caster would no such thing because of those stories, you see? It's a big gauche.

[And no one wants to be seen or treated like a witch of old. Well, most caster don't.]

But I'm no expert, not being a spellcaster myself. I only go by what my friends and acquaintances have told me.