[jgibson]

They are manual in the sense that there is a physical connection: the steering wheel is usually mechanically coupled with the steering rack, brakes usually through through hydraulics.

That said there are probably 5-20 systems in a car that can completely control these systems without any human input. Think of automatic emergency braking, traction control, vehicle stability control for the brakes, and autopark + powered steering for the steering.

Most of these systems have multiple redundancy and isolated monitors (eg, if autopark is on and the vehicle speed is > 10mph, the monitor will intervene) but there are still probably some theoretical situations where this could occur