A Starbucks dead zone

There's a "Starbucks dead zone" west of Boston, almost centered on the DoubleTree Hotel in Waltham. You can see it on Google Maps. When I looked at the search, point A in Waltham is a bookstore with a cafe that serves Starbucks coffee, not an actual Starbucks store. If you look closely, you can see the other matching dots around the west, in Bedford, Concord, Sudbury, Wayland, and Wellesley. It's not a perfect circle, but it's a nice ring.