My category for AI is based on "popular perception", not necessarily an actual comparison to what humans can or can't do. Most humans don't know how to multiply complex numbers, but that doesn't mean doing so demonstrates human-level intelligence and decision making.
In the specific case of cruise control, I don't think maintaining speed accurately is typically viewed as "difficult" for a computer today, so it would be deceptive to refer to as AI. 100 years ago that may have been different.
In the specific case of cruise control, I don't think maintaining speed accurately is typically viewed as "difficult" for a computer today, so it would be deceptive to refer to as AI. 100 years ago that may have been different.