Electronic power steering already exists. It's used in a lot of cars, and has been for at least 10 years. Your car may have one of these systems in it.

In an electric power steering system there are steering angle and torque sensors that know what direction the wheel is turned an how hard it has turned, and this is connected to an electric motor that powers the gears to move the steering rack.

There are still regulations in place that require a mechanical connection to the steering wheel and rack, but try and turn the wheel with the car off and see if your wheels move... But when the car is running when you turn the wheel you're just a voting remember in the system.

There are no such regulations for throttles. Pretty much every car since the late 80s has electronic throttle control and there are no mechanical linkages from pedal to throttle body.