The fact missing out here which no one noticed is the prices.

The prices of food items on Zomato are always higher than that served at the restaurant.

The restaurant owners are always changing the prices and still complain that Zomato is cheating them by offering discounts.

Also they forgot the fact that without zomato it would have so difficult for them to discover and serve. Basically they want the entire business of zomato without any cost.