system
A chat on subreddit /r/NoStupidQuestions
human
I've also met a number of vegans who won't eat food cooked in or on surfaces that have previously been in contact with non vegan food.  Is there a legitimate physical reason for this behavior or is it just more sanctimony?
gpt
That one may be for a couple reasons. The legitimate one being, that if someone has an allergy to some animal product, then cross contamination could make them sick. 

Non allergy related, not sure.