> A driver can respond to a visual stimulus in a few hundred milliseconds, and decide an action, such as making a turn. So the computational depth of this behavior is only a few tens of steps. We don't know how to make such a machine, and we wouldn't know how to program it.

IMHO, that makes no sense. Assuming we have a really large state machine with all many possible situations in a state of driving on a straight highway with a few vehicles with more or less constant relative velocity, determining if we need to make a turn is definitely doable in a few computation steps.