Roasting and heat treatment do not alter the allergenicity of peanuts or tree nuts. This is currently perfectly legal. Fortunately most supermarket chains and many manufacturers now assist allergic customers by declaring the presence of peanuts and tree nuts on ingredient labels regardless of this rule. In addition, some companies produce lists for customers of their own-brand lines which are guaranteed free of peanuts and tree nuts. It is important to read food labels thoroughly, even if you are buying a product you have eaten before without difficulty.
Recipes do sometimes change.
Cereal bars, confectionery. Vegetarian products such as veggie burgers. Salads and salad dressings. Satay sauce, curries, Chinese, Thai or Indonesian dishes. Remember that the above list is not exhaustive.