Nobody is driving. It digs whether you watch or not.
No two runs are the same and nothing here is scripted. Each ant only knows four things: whether it is carrying a grain, which way it was already heading, what is directly in front of it, and roughly which way is up. Everything else — the shafts, the side galleries, the chambers, the spoil heaps growing on the surface — is what happens when eighteen of them follow those four rules at once.