Anyone know how the game picks which sims visit community lots?

@citysimmer I think I've seen that somewhere as well about certain lots spawning different ages groups. I got to thinking about it because it baffles me sometimes the sims of my own that I see out and about sometimes, when I know full well they'd be at home with the kids rather than walking around town. I also wonder if it has something to do with whatever household your playing, or have recently played. Thanks for the feedback.