Once, when working in a health food restaurant, a disgruntled mother approached me. It was an open kitchen and one of the servers had pointed me out as the pastry cook. She wanted to know what her children could eat off the dessert menu since they were lactose-intolerant, gluten-intolerant, allergic to nuts, and didn't like chocolate.
"Fruit?" I suggested.
She threw my ingredient book at me and stormed off. I wasn't trying to be cheeky, but I really didn't have much dessert-wise that would fit every dietary issue her kids had. We did gluten-free, but those options included nuts. We did ice cream, but it used goat's milk. And chocolate was all over that dessert menu.
In restaurants, most adopt the attitude, "If we can, we will." I gladly would have cut some fruit for her kiddos. We want you to have the best experience as well as a great meal in our establishment. Unfortunately, not only do we not know the guidelines for every diet that exists, but there are times when we just don't have the ability to make substitutions.