Just because a driver has less things to attend to does not mean he is less attentive. In fact, I would argue a person becomes less attentive to any given thing

Just because a driver has less things to attend to does not mean he is less attentive. In fact, I would argue a person becomes less attentive to any given thing the more things there are they have to pay attention to. Burdening a driver with more (arguably unnecessary) cognitive load is not a good idea.