A town people message on the way
Tindivanam's position explains its WhatsApp traffic. It is far enough from Chennai that travellers plan a stop, close enough to Puducherry that a cab ride is an easy booking, and on a suburban line that brings people in and out every day. Much of what a business here receives is a question sent from the road.
That favours replies over broadcasts. A lodge, a cab owner or a grain shop that answers the first message well, and then sends one clear utility note when something is ready, uses the cheapest kinds of message and never needs to chase anyone with offers they did not ask for.