How does a restaurant contribute to a tourism industry?

They are a massively influential element in a society's economy.

1) They provide jobs for both highly trained/skilled employees (chefs), experience-trained (cooks) and untrained (busboys, waiters and dishwashers.

2) They are consistent, predictable and active purchasers of both fresh and manufactured foods used to prepare the meals

3) They are consumers of secondary elements like tablecloths/napkins (and the laundry), beverages, glassware/cutlery/dishes as well as services of Accountants and lawyers.