I'll take a stab at this one. When you wear the mask going and leaving the restaurant it can protect you from getting a dose of the china flu as you are passing customers leaving and going in the restaurant, standing in line waiting to be seated and you are passing by the tables. Sitting at the table better isolates you ie. social distancing. The mask doesn't prevent the virus from getting you but the experts say it can lower the viral load.I love the ones that wear em into a restaurant and then take them off when they sit at their table. That Covid is one crafty virus. It'll getcha in the parking lot, but not at your table. It lurks in churches, but not casinos. And it runs rampant in schools but is not allowed in liquor stores. Yup! One crafty little virus.
At least that's the only reason I can come up with.