One the few really good things about being an adult* is that you could, in theory, eat what you want whenever you want and nearly everywhere¶ you want.
So, don’t spoil that by telling someone what’s allowed on an pizza or not. There’s no DOP on pizza, even if it is on the UNESCO world heritage list, and I am a grown person who can obviously decide myself if I ruin myself indulging in fried mars bars!
Oh, wrong example. Pineapple. I meant to say pineapple.
'* restrictions apply if you aren’t a wealthy white male living in an industrialised ‘western’ country on the northern hemisphere.
¶ restrictions apply in libraries, transportation, any private place which doesn’t belong to you and every public space.
As I understand it the evidence for this is weak, and it’s more likely that in San Francisco just like everywhere else you get the yeast and bacteria that were present in the flour you started with.