"No-shows" aren't applicable to all types of restaurants. It is generally applicable for fine dining restaurants and restaurants that have a high traffic of diners.
There are measures which can be taken to reduce no-shows, such as making the guest pay a non-refundable deposit. I find this is by far the most effective method to ensure guests are more likely to turn up at the restaurant.
Another more lenient option is to inform the guests that if they do not turn up on time, their table will be available for any walk-in guests. Inform guests of the specific time that the table will be held till. The objective of these measures is to ensure the customer understands the demand for the tables at your restaurant and to ensure they respect your business practices.