<<Landing in very poor vis is/was not the end of the matter. Airport authorities presumably then need to have some assurance that aircraft can navigate to a gate without accident? Just a thought.>>
Where I worked there was ground radar and controllers had to display their ability to navigate aircraft around the airfield before they validated. There were regular exercises using AFS vehicles during night watches where the fire vehicle would have the windscreen covered so the driver depended entirely on ATC for guidance. I excelled myself by steering one such vehicle into a pair of engineering steps which were not showing on the radar! Wonder if they still happen?