I'm sure this was intended sarcastically. On the surface it would seem that wearing a mask alone in a car isn't going to help you at all, and while you're alone

I'm sure this was intended sarcastically. On the surface it would seem that wearing a mask alone in a car isn't going to help you at all, and while you're alone in your car it doesn't but there are scientific reasons it could have been logical to do so. Once you've used your mask you're supposed to throw it away, because there is potentially virus on the outside of it. You are even supposed avoid touching the outside of the mask when you take it off. The other reason that comes to mind is, it could just help the remember to have it on when they go from place to place.