I think that this may reflect a difference in the UK versus North America-- that is, we're used to a _______ Restaurant, that offers an option to order menu items to go.
THERE, there exist establishments in cities in particular, but also in villages that we visited, where space is at such a premium that they aren't really "restaurants" in the North American sense at all. More like catering kitchens or something-- with a window for pickups.
MANY MANY MANY of those types of establishments use peanuts or cashews in particular because of the incorporation of Indian cuisine into the UK lexicon. It's much like the permeation of some types of Asian cuisine into western N. America-- it's truly in EVERYTHING.
The bottom line is that MOST take-away restaurants should be considered "Chinese" or "Indian" in that model because of what they handle and prepare. Having seen how tiny the kitchen space is in a few places in the UK-- no way could there be a way to prevent XC in this kind of food preparation.