I think it can be normal. Maybe they are sitting where there is free internet access, or maybe (and I do this VERY OFTEN) listening to a news story (NPR has a name for it, they call it Driveway Moments, when you stay in the car listening when a story is just that good). In this time of COVID, access to wifi, and sometimes even shelter, has driven many people to spending more time in vehicles than they might normally.

Our library intentionally leaves Wifi on for this reason, whereas it used to be shut off when the library closed and turned on when we reopened.

All I’m saying is that there are many possible explanations, and there may be no reason to be, as you yourself put it, paranoid.