You can't catch polio twice. And chicken pox is pretty similar to covid actually. It has a similar R value, and adults who catch it can be hospitalized, but for children it's usually not as serious. And once you've had chicken pox you have strong immunity, although you can still get some of the symptoms if exposed.

As for comparing restaurant and school. Schools are publicly funded and mandated by the state. No one has to go to a restaurant.