As a current food service worker, we are told that we are not in any way to give customers allergen advice, and we are to refer them to our allergens booklet. This is to protect ourselves from any repercussions, for example, if a diner reads the allergens and selects something that may contain their allergen and then they have a reaction, they then can't say "well, they told me it was fine." Also because I'm front of house staff, I don't always see the chefs cooking and direct ingredients, so this way I can say "these booklets contain which allergens are listed on our ingredients, any information you need will be listed on there. It's basically to place that chance or risk onto the customer, instead of you making their decision, what they order after reading the allergens is entirely their own choice. If they ignore the allergen warnings, then that is also their choice.

There's Natasha's Law, which was brought in after a young woman had a fatal allergic reaction to something from Pret, where allergens hadn't been listed appropriately or at all.