Nope, ColPAS and ParPAS solutions both normally have the mechanical connection of the steering column between the rack and pinion mechanic and the steering wheel, they mainly differ by the way of introducing the mechanical assist force to the system. (on the steering column, or at the rack and pinion mechanism).

They generally have the following root safety requirements:

- the assist system must not cause "blocking" (unturnable wheels/steering wheel)

- the assist system must not cause unintended steering

- the assist system must be able to restart in less than 20 milliseconds

- the assist system must stay passive after a number of unsuccessful startups/unrecoverable errors (typically 3). In this case the mechanical steering column still provides a way for the driver to control the car.

It has been 10+ years since I last worked such a system, but drive by wire was only on the horizon, not the norm, and as far as I know the authorities only allowed drive by wire solution some 2-3 years ago, with product development lifecycle of around 5 years that means they are still not the norm among new cars I believe.

Back then more redundancy in the electric motors (more gradual failure if one phase goes bust, not going into deadlock in certain angles when any of the 3 phases is malfunctioning) and authenticated communications on the system bus (which was considered trusted earlier) were on the roadmap for the next gen steering systems, which are mandatory requirements before you can get to steer by wire.

No. Almost all cars except some concepts and prototypes have mechanical link between the steering wheel and the steering rack. Even if the link is augmented by a hydraulic or electronic booster.

If a booster fails you have a chance of overpowering it, it's not that strong. A faulty steer-by-wire will swing you into the oncoming lane with no recourse.