[usehand]

I never said mirrors should be replaced.

Also, this conversation is about backing up and parking (read what I said). When backing up you are mostly looking backwards only, so the focal length adjustment point is moot. Even if you have to switch to looking forwards, this is at low speeds / standing still, so it doesn't make a difference.

I'll restate my point with emphasis because you seem to not have read it: Cameras are infinitely more useful for backing up and parking.