California has one of the stricter shelter-in-place orders and everything connected to food supply, including prepared food, is essential. Restaurants are delivery/takeout only, but still operating.
Now, it's probably true that on average the share of food consumed from restaurants has dropped, but the sector isn't closed down.
I'd imagine though that people are still eating roughly the same amount of food, so if restaurant sales have dropped then grocery store sales must have gone up (which I guess they did given the hoarding).