common > , the only was to be assured is to buy the seat next to yours.
again, my understanding, they don’t sell empty seats. Maybe I’m wrong. But looking at this Jewishly, our approach is different: if I am bothering you, it is my responsibility to mitigate the damage (Bava Basra, 2 houses at different height, the one higher needs to put the fence). So, a kosher obese person should be buying enough space and a kosher non-masking (oxymoron, IMHO) people should all bunch together in the back of the bus.