A misconception that vegans are "...greatly more difficult" to cater for due to a "restrictive" and/or "extreme" diet. Basic plant based carbs that you would get at controls such as potatoes, beans, pasta, bread, fruit and dry cereal are all vegan.
Bread's a standard gotcha. It's not uncommon for whey powder to sneak in there. I'd want to check the ingredients on baked beans too (I know proper Heinz ones are fine, but cheaper brands might not be).
This is the sort of thing that doesn't occur to people without experience of what to check for. Common sense only gets you so far.
And to reinforce this point, I made a shepherd's pie this evening and was going to grate some cheese over it before sticking it in the oven. I glanced at the Gran Padano packaging before opening it, and noticed that there was an ingredients list. Lysozyme protein from egg.
Egg in any quantity is likely to send my wife to hospital: a bit of protein, in a bit of grated cheese, topping a more substantial dish? She might get away with it, she might notice a mild reaction and get away with chewing some antihistamines and rest. But it was easier for just me to have cheese tonight.
(On a similar note, much gluten-free bread contains egg. Bit of a pain when she can't have wheat either, and invariably missed by restaurants when they proudly offer it to her.)