Why do people dining at the restaurant? How do the staff manage the complain of the diners? Is it relevant to give complimentary food while waiting?

As every person is running from stress and every day the people used to have there food in there home so time people wants to eat restro food to make them happy and relaxed so they prefer restro food.

Giving complimentary food is loss for the resro but they have to satisfied there guest also so instead of that provide juice,mocktails,tea N coffee.what i used to do.Because the beverage costing is low then food