The cops in the checkpoint

The checkpoints are installed in the boundaries of the towns and cities. That is to discourage people from traveling since the virus spreads faster due to the traveling people. The idea is if everyone stays at home then the virus will be stagnant and therefore would vanish. Manning the checkpoints are policemen authorized by the local mayors.

Since the face mask is imperative for people going out of their homes, I wonder why the cop in the checkpoint said that we should be wearing a face mask when we are in the car. That does not make sense to me since my car is a private property and not a public transportation. It is like telling me to wear a face mask when I am at home.