The one that baffles me is the people who wear a mask nowhere but an airplane. Maybe it's just a remnant of the fact that airplanes were the last place you had to wear them, but studies actually show that the air circulation on planes actually makes catching respiratory illnesses less likely than in other enclosed public spaces.
And that's not uncommon. The last time I traveled, maybe 10-15% of people were wearing masks versus virtually nobody at home.
My mother is one of these people; I think it comes down to anxiety about the churn of people coming from all over. Doesn't make sense in an era where covid is totally endemic everywhere of course.