Not an example from France, but I've experienced captive portals elsewhere that give temporary access for 10-30 minutes which gets extended when you click on a

Not an example from France, but I've experienced captive portals elsewhere that give temporary access for 10-30 minutes which gets extended when you click on a verification link they email you. I don't expect bar owners to develop such a system, but if too many people do fake info, the government might lean on the providers of the off-the-shelf solution to which the bar owners subscribe to add that functionality.