Linate does have ground radar but it is been out of action for two years! On the PPRuNe forum someone published details of the low visibility procedures at Linate. These clearly indicate that the Cessna was completely in the wrong place. The taxiway it was on and the route it used to get there are closed during low visibility. If ground radar had been working the controller would have seen the Cessna in the wrong place and ordered it to stop. It seems the cause is human error compounded by the lack of suitable working equippment.