Agree, and you get to see how the other person treats other people (waiters) or handles adversity (a bad meal, wrong order) or whether they have patience (if you have to wait to be seated or for the meal.
You learn a lot.
When I'm hiring for anything other than entry level people, I always take them to lunch. Good way to find out how they interact in the real world. For instance, it's a *sandwich*. It shouldn't take 20 minutes to agonize over the decision, or quiz the server on how rare the roast beef is, or what the cow's name was.
I had one candidate who I'd made up my mind to hire. Sharp kid. Right out of college. Bright, personable, fit in well with the guys. Lunch was going to be a formality...... until he drained three beers (in an hour), made a pass at the waitress, and was a general boor. That was a bullet dodged.