I loaded the Prescott family to check and found Tomax Collette at the grills near Town Square Terrace. The Prescotts live at Golden Peak, rather than Water Tower Way, but it's still the same neighborhood. I also found one Sim next to Thriftea, two Sims at the chess table next to the fountain, and four other Sims scattered around the Pink Hat store by the traffic lights. I think the picnic tables you mentioned are the ones near the grills, so I have at least one Sim who will wander further than yours seem to.
I played the family living at Golden peak, was the Amicable family from the magic expansion at the time. Sat zoomed out and fast forwarded for 12 hours and only a single sim crossed the line from where the Thriftea shop sits, and it was a child who went to the monkey bars to play. I did have a few visitors who came to the house, but not a single sim was anywhere near the grills or park benches. I think 1 sim did walk to the chess sets near Thiftea as well.
