DMcG posted at 01.46 about the use of certification papers. I live most of my life in France (although am in the UK due to the virus stopping travel) and over there the use of certificates is required for all activity outside one's own property.
The forms have to be printed off the government website and contain a list of things that are acceptable, such as shopping, exercise, doctor/pharmacie visits, caring for relatives I think and a couple of others. You also have to take a form of identification (only passport, photo driving licence, Carte de Sejour) and these are checked along with the form. A new form is required for each activity and it is very strictly enforced with police or army checks even at some supermarkets.
I'm not saying this is the way forward, just that it is being done with no apparent 'black market' or identity theft. People, in the main, seem to be adhering very strictly to the rules over there.