That's what I thought too. Looked so simple, yet in practice I bet not so easy to get the angles right so they flip reliably.
Every time i see them running, i swear it's like sorcery as they all flip over to the right way up
They are so simple in concept, but someone needed to think of it in the first place. Not sure it's something i could have come up with. My idea was to make exact projectile shapes in the wheel, so they can only go in one way then hopefully fall the same way each time.