It's baffling how the authorities expect to trace everyone a potential positive has been in contact with. If that carrier is asymptomatic and innocently carrying on as normal, and if they are shedding virus that can survive for a short time on hard surfaces, surely even putting fuel in their car can involve touching the pump handle, the door to the shop part or the 'pay at pump' keypad. What if they wiped a tickly eye before getting out of the car, blew their nose without washing their hands before refuelling, or had been eating in the car - using fingers, not cutlery - what if they'd nibbled a broken nail before handling the fuel pump, before laying their keys on the counter while paying?
Italy are restricting the number of people allowed inside supermarkets or restaurants so the density of people allows a metre space between them. That won't make a difference if carriers touch the same door handles, keypads, the same products if they pick something up to read the label and then put it back on the shelf. All the time there is a possibility of transmission on surfaces, there is no way to identify the trail of people who touch the same item with just minutes or seconds in between.
I work in a supermarket and view every customer's hands as potential sources of bugs, but I've felt that for as long as I've worked there. It's not just the flu... but even so I am over 60, I've had flu twice in my life and the last time, 7 years ago, I was getting over chemo and was very ill with it, I don't want to get that or any other RTI again.