I don't see how it's low-risk to have an infected person preparing your food in the kitchen.

At least with a grocery store, you can wash off the produce before you use it. With a restaurant, there's nothing covering the food at all.

And remember, the chefs in the kitchen are paid peanuts, and have no safety net whatsoever, so there's zero incentive for them to get tested or to stay out of work if they get sick. This is also the case during normal times. Eating out is a good way to catch something in a country where we think it's a great idea to fire cooks and other low-wage workers when they call in sick.