Don't understand what purpose it serves. You only have to isolate it you are within 2 metres of an infected person for more than 15 mins. Why would you be within that distance in a restaurant or cafe unless they were at your table? And in which case, you would have to give their details to contact tracing people anyway - same as you do for any contact outside hospitality? No one logs where anyone is sitting anyway or how long you are there for, so I don't see what the point is in collecting all this data on who visits what venue?