Why would someone who was on there own in a car wear a face mask ?

I always thought the same way. However it is a matter of habit I think, because if the driver is not wearing the mask he will forget to put it on when getting off or interacting with other people. That's the only justification I give it, but I still think it's a bit unnecessary. It's like people who are at home wearing a mask 24 hours a day, it's crazy.