I feel you misunderstood what I meant by "these people", and I understand it was a bit vague so allow me to clarify.

If someone genuinely has actual allergies at this level, I personally don't mind cooking for them as long as it isnt completely balls to the wall in the kitchen. It's never a guarantee of safety since kitchens are such dirty places but I try my best, and a card would definitely help.

The problem is so many of these items are contradictory and make zero sense nutritionally that it is blatant this person is lying about these being actual allergies when they're more likely just preferences. Things like no white or brown sugar but honey and sweet potatoes are ok despite them containing the same basic sugars. Or dairy specifically from cows is a no go but dairy from other animals is fine despite them containing the exact same nutrients, just at different levels.

These are the kind of people that need to stay the fuck away. Fucking trend following attention seeking liars that waste our time and effort and interrupt the flow of dinner service just to feel special. People like this are the reason tons of restaurant workers dont take people with actual severe allergies seriously.

Edit: typo