I live in China (Shanghai). In public places everyone here is masked. I was pretty sure that it is sufficient, then I noticed that at home and in restaurants

I live in China (Shanghai). In public places everyone here is masked. I was pretty sure that it is sufficient, then I noticed that at home and in restaurants the habit of sharing plates while eating persists. It seems to me that it enables people to 'share saliva'. Many, but not all, rather skillfully use their chopsticks to only take whatever they want, avoiding contact with anything else. However a chopstick is often in contact with food remaining in the plate, especially whenever there is sauce or liquid, or with the plate itself. How comes this practice doesn't seem to enforce virus propagation?